ok so much i found already just looking at the levels in pain editor
theres a lot of reusing happening in the level geometry which lead me to believe they have some magic trick up their sleeves to display ligthmaps on instances but they don't the instances are all actually merged together into one big mesh very memory inefficient
and sucks to change in maya if you have one fucked up ploygone you have to fix it 100.000 million times
alla actualy instanced things guns pickups enemys phys objects are all tnl lit D:
next i am gonna look at how they handle their materials i am extracting their textures form the pak file right now to take a closer look (with this little helper http://forum.xentax.com/viewtopic.php?t=732) it seams they have like all their material of the level on one sheet except for the floor you can tell because sometimes theres no UV cut next to a high res trim they just do clever reusing *kudos for that* analysis will continue