STLLR Gold Delivers Updated Mineral Resource Estimate and PEA Demonstrating US$1.0 Billion After-Tax NPV5% for the Large-Scale Tower Gold Project in Ontario, Canada o Average annual gold production of 273,000 ounces for 19-years, including peak

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STLLR Gold Delivers Updated Mineral Resource Estimate and PEA

Demonstrating US$1.0 Billion After-Tax NPV5% for the Large-Scale

Tower Gold Project in Ontario, Canada

o Average annual gold production of 273,000 ounces for 19-years, including peak

average annual production of 316,000 ounces over the first five years, and a

maximum annual production of 325,000 ounces in Year 15.

o 5.2 million ounces of gold production over the 19 years of conceptual mine life

(“CML”).

o Base Case After-Tax NPV5% of C$1.36 billion (US$1.01 billion) and IRR of 13.4% at

US$2,500/oz gold.

o Spot Price After-Tax NPV5% of C$3.30 billion (US$2.46 billion) and IRR of 24.0%

at US$3,200/oz gold.

o 2025 MRE (as defined herein): 4.0 million ounces from 140.4 Mt grading 0.89 g/t

Au in the Indicated category and 7.0 million ounces from 200.3 Mt grading 1.08

g/t Au in the Inferred category.

o 2025 PEA (as defined herein) is preliminary in nature and includes inferred

mineral resources that are considered too speculative geologically to have the

economic considerations applied to them that would enable them to be

categorized as mineral reserves, and there is no certainty that the 2025 PEA

will be realized. Mineral resources that are not mineral reserves do not have

demonstrated economic viability.

TORONTO, ONTARIO May 15, 2025 – STLLR Gold Inc. (TSX: STLR) (OTCQX: STLRF) (FSE: O9D) (“STLLR”

or the “Company”) announces the summary results of the updated Mineral Resource Estimate (“ 2025

MRE”) and updated Preliminary Economic Assessment (“2025 PEA ”) for its 100% -owned Tower Gold

Project (“Tower” or the “Project”) located in the prolific Timmins Mining Camp in Ontario, Canada. The 2025

MRE was prepared by InnovExplo (a member of Norda Stelo) and the 2025 PEA was compiled by G Mining

Services (“GMS”).

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Table 1: 2025 PEA1 Economics*

Potential Economics

Gold Price Assumption

US$2,500/oz

Base Case

US$3,200/oz

Spot

Pre-tax internal rate of return (“IRR”)(%) 16.1% 28.6%

After-tax IRR 13.4% 24.0%

Pre-tax net present value at 5% discount rate (“NPV5%“)(C$M) C$2,118 C$4,961

After-tax NPV5% (C$M) C$1,355 C$3,298

CML after-tax free cash flow (“FCF”)(C$M)2 C$3,438 C$6,739

FX rate assumption (USD/CAD) 1.34 1.34

After-tax NPV5%/Initial Capex ratio 0.7x 1.8x

After-tax Payback period (years) 5.8 2.9

*Figures may vary slightly due to rounding

Table 2: 2025 PEA1: Conceptual Mine Plan Summary*

Metrics CML Total Per Unit

Conceptual Mine Plan

CML 19 years

2025 MRE conversion to conceptual mine plan 52%

Total mineralized material (million tonnes “Mt”) 176.9 Mt 9.5 Mtpa3/26,030 tpd3

OP material during ramp-up 1.4 Mt

OP 148.8 Mt 7.8Mtpa3/21,370 tpd3

UG 26.6 Mt 1.7Mtpa3/4,660 tpd3

Total OP waste rock mined (Mt) 652.7 Mt

Total OP overburden tonnes (“OVB”) mined (Mt) 288.3 Mt

Total OP waste (waste rock + OVB) 940.9 Mt

Strip ratio, excluding OVB 4.3

Strip ratio, including OVB 6.3

Average mill gold head grade (“g/t Au”) 0.99 g/t Au

CML OP production 0.75 g/t Au

CML UG Production 2.35 g/t Au

Average mill recovery rate (%) 92.7%

Total potential payable gold production,

excluding pre-production (thousand ounces “Koz”) 5,191 Koz 273 Koz/year

Pre-production gold recovered, OP ramp-up 43 Koz

OP production

UG Production

3,326 Koz

1,868 Koz

175 Koz/year

98 Koz/year

1 Please review the “Cautionary Statement regarding the 2025 PEA” at the end of this news release.

2 Free Cash Flow is a non- IFRS financial measure. Undiscounted and net of Initial and Sustaining Capital Expenditures (“ Capex”), and Operating

Costs (“Opex”). The Company does not currently have operations and therefore does not have historical equivalent measures to compare to and

cannot perform a reconciliation of this non-IFRS financial performance measure.

3 Million tonnes per annum (“Mtpa”) and tonnes per day (“tpd”)

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Metrics CML Total Per Unit

Capex and Opex

Initial Capex (with contingency) (C$ millions “M”) C$1,873 M

Pre-production revenue (C$M) C$144.6 M

Sustaining Capex4 (excluding Closure/Salvage) C$1,723 M C$91 M/year

Total Cash Costs5 C$8,901 M C$1,715/oz (US$1,280/oz)

All-In Sustaining Cost (“AISC”)6 C$10,700 M C$2,059/oz (US$1,537/oz)

All-In Costs (“AIC”)6 C$12,575 M C$2,403/oz (US$1,793/oz)

*Figures may vary slightly due to rounding

STLLR President and CEO Keyvan Salehi, P.Eng. commented: “Tower is one of Canada’s largest

undeveloped gold projects, with size and scale matched only by a few Canadian gold projects . The 2025

PEA showcases the potential to produce 2 73,000 ounces of gold annually over 1 9 years, with peak

production of 325,000 ounces. We believe the 2025 PEA delivers compelling economics with defensible

capital and operating cost estimates. We designed the conceptual mine plan to maximize the output, which

we believe is the best path to advance the Project and deliver long-term value. Furthermore, it is also our

view that the geological environment hosting the Project continues along strike and at depth with solid

upside potential for exploration. We believe this mine plan represents a strong foundation for a project with

meaningful potential to grow in size, scale, and conceptual mine life.”

“The 2025 MRE and 2025 PEA represent major advancements for Tower. We rebuilt the geological model

from first principles, integrating detailed structural and lithological data to better represent the gold

mineralization. Our disciplined approach has strengthened the 2025 MRE, increasing confidence and

credibility, while laying the groundwork for more targeted and efficient future drilling. The Tower deposits

remain open at depth and along strike to the west and east, with strong potential for expansion. In tandem,

the mine plan was also developed using a comprehensive, bottom-up approach grounded in first principles,

delivering a technically robust and executable strategy. Opportunities to grow the known mineralization ,

optimize the mine plan, and enhance project economics will continue to be pursued aggressively. Pre -

Feasibility Study work is underway, with completion targeted for 2027. In parallel, we are advancing

permitting efforts to potentially bring Tower to shovel-ready status by 2029. We believe Tower is one of a

select group of large -scale gold projects in Ontario with a clear path to development in the foreseeable

future.”

4 Sustaining Capital is a non-IFRS financial measure. The Company does not currently have operations and therefore does not have historical

equivalent measures to compare to and cannot perform a reconciliation of this non-IFRS financial performance measure.

5 Total Cash Cost is a non-IFRS financial measure. Total cash costs per ounce are operating costs, composed of mining (UG & OP), processing, water

treatment and tailings, mine site G&A, royalty costs, refining and transport, divided by payable gold ounces. The Company does not currently have

operations and therefore does not have historical equivalent measures to compare to and cannot perform a reconciliation of this non-IFRS financial

performance measure.

6 AISC and AIC are non-IFRS financial measures. AlSC includes cash costs plus sustaining capex and closure. AIC includes AISC plus initial capex.

The Company does not currently have operations and therefore does not have historical equivalent measures to compare to and cannot perform

a reconciliation of these Non-IFRS financial performance measures.

.

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Construction and Development Plan

Located 100 km east of Timmins, Ontario, along Highway 101, the Project benefits from proximity to existing

regional infrastructure, including paved highways, power distribution, and local supply chains. Its proximity

to Timmins, Kirkland Lake, and Matheson, provides access to a skilled and experienced labour pool.

The construction plan focuses initially on the development of the OP deposits, supported by the installation

of key surface infrastructure, including a processing plant, tailings management facility (“ TMF”), and other

essential site services. The construction phase will be executed under an Integrated Project Management

Team (“IPMT”) model over a 30 -month period. Pre-production activities will begin in month 24, with first

gold production expected during the subsequent 6-month commissioning and ramp-up phase.

Stripping of overburden will commence at month 7, and OP mining operations will transition to a primarily

owner-operated model upon the start of commercial production. Note that certain functions, such as

explosives delivery to the hole, will remain under the responsibility of specialized contractors or suppliers.

During the construction period, approximately 58 Mt of OVB will be removed to access mineralized material,

with an additional 230 Mt of OVB scheduled for removal over the CML. Upon completion of mill construction,

approximately 1.4 Mt of OP mineralized material is expected to be processed during the commissioning

period, yielding an estimated 43,181 ounces of pre-production gold.

UG development will begin after the 30-month construction phase and the commencement of commercial

production. U G development will focus on lateral development, including the establishment of multiple

ramp systems from surface, and the staged acquisition of mobile mining equipment. Over the CML,

approximately 191,033 metres (“m”) of lateral development is planned, providing access to 5 mining zones

within the UG deposit.

Conceptual Mine Plan

The Project’s 19- year conceptual mine plan contemplates the O P and UG mining of mineralized material

from two primary areas: Golden Highway (western extent) and Garrison (eastern extent).

OP Mining: The OP mine plan is based on conventional drill, blast, load, and haul methods utilizing double

benching of 10-metre benches. The Windjammer deposits (South, Central, and North), located within the

Golden Highway Area, contain the majority of the OP mineralization. A total of seven (7) pits with up to three

(3) phases each are planned over the CML to sequence mineral ized material and manage strip ratios at

Golden Highway and Garrison.

OP production is designed for a throughput of approximately 22,000 tpd, or 7.8 Mtpa, at an average head

grade of 0.75 g/t Au. The average strip ratio is estimated at 4.3:1 (excluding OVB) and 6.3:1 (including OVB).

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The 2025 MRE and 2025 PEA reflect increased estimates for waste rock and OVB relative to the 2022 PEA7.

These changes are primarily attributable to:

MRE

• A reconstructed geological model, developed from first principles, which integrates updated

structural and lithological data for improved representation of mineralization geometry.

• New geological data from the infill drilling programs has been incorporated in the latest domaining,

which more confidently models the mineralized vein domains. This refinement has led to reduced

mineralized material and increased classification of surrounding material as waste.

PEA

• The adoption of an engineered first-principles pit design, inclusive of ramp placement and minimum

mining width constraints, which has decreased overall slope angles and increased waste volumes.

• Revised geotechnical parameters, resulting in shallower overburden slopes and, consequently, larger

overburden volumes.

UG Mining: The UG mine plan employs a mechanized long-hole stoping method, accessed through multiple

surface portals and ramp systems. Stopes will be mined in a bottom-up sequence, drilled and blasted, and

then backfilled with either cemented rock fill or uncemented rockfill , depending on geotechnical and

operational requirements.

Planned stope dimensions average 25 .0 m (height) × 20 .0 m (length) × 11.5 m (width), with an estimated

average stope tonnage of 14,490 tonnes (inclusive of dilution and mining losses). UG operations are

expected to contribute approximately 4,760 tpd (1.7 Mtpa) to the mine plan , supported by a consistent

cycle of stopes in development, active mining, and backfill phases throughout the CML.

Potential Production: With a 92.7% mill recovery (see “ Processing” section), the project is expected to

produce 5.2 Moz of payable gold over the CML, averaging 273,000 ounces annually for 19 years (see Tables

2 and 3 and Figure 1 for more details on the conceptual mine plan)

Table 3: 2025 PEA – Conceptual Mine Plan*

OP UG Total

Material Waste

Rock OVB Grade

Milled

Contained

Gold Material Grade

Milled

Contained

Gold

Contained

Gold Recovery Payable

Gold

Year (Kt) (Kt) (Kt) (g/t Au) (Koz) (Kt) (g/t Au) (Koz) (Koz) (%) (Koz)

-2 27,828

-1 1,437 12,060 30,060 1.08 50 50 86.6% 43

1 9,225 32,184 28,117 1.05 312 1 1.89 0.08 312 91.5% 285

2 9,056 25,865 29,900 0.76 223 364 2.43 29 251 92.5% 232

3 8,016 31,925 30,005 0.91 233 1,480 2.43 115 349 88.9% 310

7 For more information on the Tower 2022 Mineral Resource Estimate (“2022 MRE”) and Preliminary Economic Assessment (“2022 PEA”) effective

as of September 7, 2022, please refer to the NI 43-101 technical report titled “NI 43-101 Report & Preliminary Economic Assessment of the Tower

Gold Project Northeastern Ontario, Canada”. The 2022 MRE and 2022 PEA are not current and should not be relied upon, they have been

superseded by the 2025 MRE and 2025 PEA respectively.

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OP UG Total

Material Waste

Rock OVB Grade

Milled

Contained

Gold Material Grade

Milled

Contained

Gold

Contained

Gold Recovery Payable

Gold

Year (Kt) (Kt) (Kt) (g/t Au) (Koz) (Kt) (g/t Au) (Koz) (Koz) (%) (Koz)

4 7,752 30,588 29,831 0.83 207 1,745 2.34 131 339 93.4% 316

5 7,770 46,683 12,535 0.64 160 1,739 2.00 112 271 92.9% 252

6 7,755 34,664 25,007 0.66 164 1,756 2.22 125 289 92.8% 269

7 7,741 59,511 2,748 0.78 193 1,732 2.16 120 314 92.8% 291

8 7,821 61,921 258 0.74 187 1,711 2.27 125 311 92.8% 288

9 7,647 61,842 - 0.65 161 1,641 2.29 121 281 92.9% 262

10 7,787 49,256 - 0.59 147 1,719 2.37 131 278 93.0% 258

11 7,680 37,168 - 0.65 161 1,767 2.30 131 291 92.6% 270

12 7,787 27,898 4,212 0.60 150 1,724 2.30 127 277 92.9% 257

13 7,791 19,156 16,673 0.65 163 1,700 2.59 142 305 93.4% 285

14 7,744 13,870 23,304 0.67 167 1,763 2.72 154 322 93.4% 300

15 7,739 30,128 6,743 0.86 213 1,722 2.46 136 349 93.1% 325

16 7,699 26,037 1,961 0.83 205 1,629 2.59 136 341 93.5% 318

17 7,657 15,970 15,345 0.72 178 1,562 2.34 118 296 92.9% 275

18 8,188 26,949 3,728 0.74 195 887 2.06 59 253 93.4% 237

19 5,922 8,993 0.89 170 170 95.0% 161

Total 150,211 652,667 288,254 0.75 3,638 26,643 2.35 2,011 5,649 92.70% 5,234

* Figures may vary slightly due to rounding

Processing

The 2025 PEA contemplates processing mineralized material through a conventional milling, gravity

concentration, and leaching circuit. The processing plant is planned to be located in the Golden Highway

Area, strategically positioned near the center of gravity of the CML tonnage to optimize haulage efficiency

across the project. The processing plant includes a primary crusher, semi-autogenous grinding (“SAG”) mill

including pebble crushing , gravity recovery circuit integrated with intensive leach reactor , two ball mill s,

followed by a Leach -CIP Carousel ( “CIL”) recovery process, Carbon desorption and regeneration,

electrowinning circuit, gold room, and cyanide destruction.

The processing plant is designed to operate at up to 26, 030 tpd, equivalent to approximately 9.5 Mtpa.

Average gold recovery is estimated at 92.7%.

Other Site Infrastructure

The 2025 PEA includes the phased construction of a conventional TMF , located in the Garrison Area (near

Buffonta) of Tower. The TMF is designed to accommodate all CML tailings generated by the processing

facility. In addition to the processing plant and TMF, major site infrastructure will include:

• A truck shop and supporting maintenance buildings

• Site-wide haul roads

• A high-voltage transmission line

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• A 400-person camp

• An effluent water treatment plant

• Surface water management ponds

• Site admin buildings, mine dry, assay lab, as well as other pertinent infrastructure

This infrastructure layout has been optimized to support phased development and long- term operational

efficiency. See Figure 2 for the proposed Tower site infrastructure layout.

Capex and Opex

Please refer to Tables 4 and 5 for the capex and opex summaries, respectively. Initial capex and sustaining

capex assume the full upfront purchase of equipment without the use of lease financing.

Table 4 – Summary of the 2025 PEA Capex*

Capex item Initial

(C$M)

Sustaining

(C$M)

Total

(C$M)

Infrastructure $123 $12 $135

Power & Electrical $214 $214

Water Management, TMF & Earthworks $135 $108 $243

Surface Operations $29 $29

Open Pit Mining $355 $769 $1,124

UG Mining $834 $834

Processing (including the mill) $265 $265

General Services (Owner’s Costs) $85 $85

Pre-Production, Start-Up, & Commissioning $187 $187

Total Directs: $1,393 $1,723 $3,115

Total Indirects $235 $235

Closure Cost & Monitoring Costs $77 $77

Salvage Value ($44) ($44)

Contingency $246 $246

Total Capex $1,873 $1,756 $3,628

Less: Pre-Prod. Credit net of TC/RC & Royalties ($144) ($144)

Total Capex Net of Pre-Prod. $1,729 $1,756 $3,485

*Figures may vary slightly due to rounding

Table 5 – Summary of the 2025 PEA Opex*#

Opex Item CML (C$M) Unit (C$/t) Unit (per oz)

Total Mining (OP+UG) C$5,935 $33.84/t milled C$1,143 (US$853)

OP mining (less capex) C$3,603 $20.54/t milled

UG mining C$2,333 $13.30/t milled

Processing (incl. power) C$2,086 $11.89/t milled C$402 (US$300)

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Opex Item CML (C$M) Unit (C$/t) Unit (per oz)

G&A C$786 $4.48/t milled C$151 (US$113)

Total operating cost C$8,807 $50.21/t milled C$ 1,697 (US$1,266)

Refining and transport C$35 C$7

1.5% royalties (Garrison) C$59 C$11

Total Cash Costs5 C$8,901 C$50.74/t C$1,715 (US$1,280)

Total AISC6 C$10,700 - C$2,059 (US$1,537)

Total AIC6 C$12,575 - C$2,403 (US$1,793)

* Figures may vary slightly due to rounding

#AIC includes pre-production costs, tonnes, and ounces

Figure 1: Annual Potential Production, Cost and FCF Profile

Taxes, Royalties, and Other Production Taxes

Corporate taxable income for operations in Ontario are subject to a combined (federal and provincial)

income tax rate of 26.5%. Tower would qualify for the Ontario manufacturing and processing tax credit.

Furthermore, the Ontario Mining Regulations require the payment of Ontario Mining Tax (“OMT”) levied at a

rate of 10.0% on taxable profits, in excess of C$500,000, which is incorporated into the financial model.

OMT is deductible in calculating taxable income for corporate purposes. In the Garrison Area of Tower, the

properties contain an average net smelter royalty (“NSR”) of 1.5%.

Economics

Using a base case gold price of US$2,500 per ounce and a USD:CAD exchange rate of 1.34, the Tower Gold

Project is estimated to generate an after-tax NPV5% of US$1.0 billion and an after-tax IRR of 13.4%. Sensitivity

2- 1- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

CML

AISC (C$/oz) 1,685$ 2,225$ 2,014$ 2,254$ 2,353$ 2,696$ 2,141$ 2,227$ 2,452$ 2,535$ 2,245$ 2,271$ 2,124$ 1,964$ 1,791$ 1,457$ 1,598$ 1,738$ 1,227$ C$2,059/oz

FCF (C$M) 106-$ 811-$ 872-$ 446$ 273$ 392$ 346$ 255$ 92$ 242$ 222$ 162$ 139$ 204$ 193$ 231$ 283$ 348$ 428$ 344$ 272$ 269$ C$3,438M

0.00

0.20

0.40

0.60

0.80

1.00

1.20

0

50

100

150

200

250

300

350

-3 -2 -1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

OP UG GradePotential Production (Koz) Grade (g/t Au)