Garry's Mod is a separate game but it works on the Half-Life 2 Engine. Yeah, it's a mod by Garry, but it's a standalone game at this point. Just like Spore, its primary support is user content creation in the form of Workshop addons, from props to ragdolls to maps to entire game modes. There is probably something for everyone and it's a blast once you subscribe to several of these addons.
One thing you can do is create ragdolls for use. Generally, I like to pose them, the main use for ragdolls, but you can, I don't know, fling their bodies around or use other mods such as Gibmod to dismember/decapitate them, especially creatures you don't like (like some ugly Maxis creatures like Fishballgirl or Bigeye Sister).
There isn't much Spore-related things in Garry's Mod, but I eventually took advantage of the built-in Collada exporter in
and I set up my beloved creature thing as a working ragdoll.
Here's a pic of it. For those living under a rock: it's on the right.
I don't really take requests because it's fairly time-consuming to make ragdolls, even if I have access to the rig (but I'd like morphers and built-in animations too...; I had to make facial morphers from scratch). But if anyone's interested, I may or may not write a tutorial on how to get a Spore creature ragdoll to Garry's Mod, right from the creator editor to a fully-functioning ragdoll with facial flexes and finger-posing.
Also, I think someone else made a Grox prop for Garry's Mod, but I can make that into a working ragdoll! But if there is a way to export these creatures more efficiently and even allow us to export buildings, vehicles, and even Adventure props from Spore, it would be great!