Jon knows what he's talkin' about! But I remember talkin' with someone who used MakeHuman as a basis for a character he was (and probably is still developing). Anyways, you may find that you'll have to get into making your models from scratch using a 3D program such as MilkShape (which is appropriate for 3D games as it allows for low poly modeling). Here's the link:
http://www.swissquake.ch/chumbalum-soft/index.html
But there are quite a few programs out there... Do a search on Google regarding 3D Game Character Modelling.
Or what you could do is use another 3D program such as
AC3D (as it appears to be pretty easy to use) and export the model into MilkShape to apply the animation ("
rigging the skeleton" as it is known) with the MilkShape FPSC animation that can be downloaded
here.
Render & Dismember. Dehumanize Society With A Digital Death Deity.