Scope of this comparison
No paid products are linked to Steam Game Idler yet, so this section compares it with the tools its own README names: ArchiSteamFarm, Steam Achievement Manager and Idle Master. The comparison draws only on what the SGI repository and website state about SGI itself, not on detailed feature checks of the other tools.
Versus ArchiSteamFarm
SGI describes itself as an all-in-one alternative to ArchiSteamFarm. Its card farming runs inside a desktop app with a visual interface, a two-phase engine, blacklists and whitelists, and up to 32 games at once. It also adds an inventory manager, free game alerts and an achievement unlocker, which keeps the whole job in one window.
Versus Steam Achievement Manager
The SGI achievement manager covers the same ground a manual achievement tool does: unlock or lock any achievement for a game you own, edit numeric stats, and see which entries are Protected, IncrementOnly or Hidden. It adds an automatic unlocker with random, human-like delays and optional schedules, so you can queue games instead of clicking through each one.
Versus Idle Master
For playtime and card idling, SGI offers a playtime booster, an automatic idler that starts chosen games on launch, and task scheduling that chains one feature after another. It runs on Windows and Linux.
Licensing difference
SGI uses the Elastic License 2.0, which allows broad use and modification but forbids offering it as a hosted service. Check each tool's own license if that distinction matters for your use.