Believe it or not, Ricochet Xtreme (often listed under the Ricochet series) is available on Steam. The Steam version is drm-free (or uses Steam DRM), affordable (often just a few dollars), and works natively on modern Windows versions. You don't need an activation code; buying it simply unlocks it in your library forever.
Originally, players had to purchase a license to unlock the full version of the game. These "activation codes" or "registration keys" were unique strings tied to a user's specific hardware. Ricochet Xtreme Activation Code 20