You can find digital CD keys on sites like DLCompare or GG.deals , which must then be activated on your Steam account. Minimum System Requirements
Windows Vista, 7, 8/8.1, or 10 (64-bit required) Processor: 2.5 GHz Memory: 2 GB RAM Graphics: 2 GB Video Memory (e.g., Radeon HD 5450) Storage: 1 GB available space Game Overview Railroads & Catacombs | Game Review in 5 minutes or Less Railroads and Catacombs Download PC Game
A free version titled Railroads & Catacombs: Prologue is also available on Steam if you want to try the game before purchasing. You can find digital CD keys on sites like DLCompare or GG