As Lead Designer on Swat: Stetchkov Syndicate I didn't get much chance to build levels or script gameplay. The screenshots below are of levels built and scripted by the very talented Dean Tate and Alex Boylan.
The expansion was very focused on multiplayer where we added VoIP, 2 new MP modes, 10 player Co-Op, 7 new weapons and a bunch of other little tweaks to the already polished game.
Swat was one of my favorite projects while working at Irrational Games. We had a small team and a very focused brief. We were building on top of a fully functional game thanks to Irrational Boston. The game was playable and fun from day one so that everything we added simply made it better. I'd love to work on another expansion pack one day.