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

Press Release

May 15, 2025

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”).

Table 1: 2025 PEA[1] Economics*

*Figures may vary slightly due to rounding

Table 2: 2025 PEA[1]: Conceptual Mine Plan Summary*

*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 273,000 ounces of gold annually over 19 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.”

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. UG 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 OP 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 mineralized 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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