Some more thoughts:
In some places you applied the "activated" switch texture (SW2*) on switches that haven't yet been used. For example, SW2SLAD on linedef 1048, right after the red door. When activated, those textures change into the "off" position (SW1* equivalent texture, so in this case SW1SLAD). This might cause some confusion.
The wall that lowers itself to access the outside secret area (linedefs 1205 & 1207) have the "lower unpegged" flag set, which gives the illusion that the texture is "unrolling" itself instead of the physical wall moving down. If the texture doesn't line up with the adjacent ones, you could uses the y-offset to adjust it instead. The outside linedef may also benefit from a switch and/or different texture, so the player doesn't get confused on how to get back in (they shouldn't, but...) SW1STARG might work okay as the lower texture (upper texture can remain as STARTAN3).
The two SW1STRTN switches in the southernmost nukage area (linedefs 1313 & 1316) seem redundant, since they're right next to each other and operate on the same corridor. It's also not immediately clear what they do. One idea might be to remove one of those switches, split the large nukage area (sector 253) into two smaller areas seperated by a wall or grate (like say in that narrow section to the north) and have the remaining switch open that passageway. Then in that corridor to the right, you would only need one obstacle (sector 283, opened by the switch behind the SLADWALL pillar).
The exit door itself seems redundant, unless you have something planned for the trek back to it from the warehouse (linedef 1671 opens up some monster closets?) If not, it probably makes sense to change that linedef type to 11 (end level). It also might be good to have a way out of those nukage pits (like teleporters, or lifts on the outermost walls).
Edit: also, it's not very clear what the switch on linedef 861 does. The player probably won't have any reason to go back down into the dark area to the south, so won't even realize he opened something there. It might make sense to relocate the switch down there, maybe in sector 140 (and have it illuminated like the lift switch) or maybe a bit to the north on linedef 732 so that it can be seen from the north before the lights go out (and then maybe it's okay to not illuminate it, since the player has a chance to spot it beforehand).
Last edited by hex11 on Oct 20 2011 at 17:04