No. Mods from 2026 require KSP 1.8+. However, the original mods for 0.15 (like MechJeb v1.6 and Novapunch ) are archived on the KSP forum. Do not install anything labeled "Version 2.0+".
If you are seeking a , you won't find it on Steam (Steam integration came later, around 0.21). You are looking for the "Squad Store" standalone version.
You have the file. You installed it. Now what? Here is a "bucket list" for version 0.15:
during the game's alpha stage, and while older "free" versions like 0.13.3 are often available on community forums, 0.15 remains a protected commercial release. Kerbal Space Program Forums Key Features Added in 0.15
: Versions as old as 0.15 are rarely available through automated storefronts. Most legacy support on Steam only goes back to version 1.0.5. Demo Version : A permanent