I've read on the forums, and I noticed that someone else has had a similar issue with this game, but the thread is several months old, and mine likely won't work, perhaps because Tango has modified the game engine to not accept SweetFX or something.
http://sfx.thelazy.net/forum/sweetfx/45/
In the above thread, some JLA_Squall linked an archive with a bunch of files to use, and it has worked for some people but me. When I installed them and tried to run TEW, it gave me an error telling me that it couldn't find a dll file from system32. Even just installing SweetFX with a configurator, the visuals remain exactly the same, no matter what preset I used. I also used Boulotaurs injector to no avail.
Anyone have any idea what might be the issue, and how to get it to work? My OS is Windows 8.1 64-bit, if it helps. Thank you in advance!