I've noticed that on map 4 where you have to look for a key, it's pretty well hidden, but it's hanging near the doorway on a wall inside a boarded-up room. I also noticed at the beginning of map 2 that it seems almost impossible to break the glass to the button without using so-called "super-guns" or "admin weapons".

Thank you for the report. I nerfed the tripmine area.

The invisible explosion was from landmine hidden under water. While other mines can be removed legitimately, the landmine cannot be removed because its 'hitbox' is interfered by water.

But since the damaging area were nerfed, you can just ignore it and proceed.

On the final map, in the hallway, you are supposed to go through the laser-tripped mines section. The reason why this is nearly impossible to pass without noclipping is that even if you manage to not touch the mines' lasers by jumping/crouching, the mines still explode and kill you anyways. Even if you manage to clear the hallway of the mines by pressing the interaction button near them, you can still be killed by hidden/invisible explosions when you try to proceed further.

The lever is locked by default, and there was no 'Unlock' input to the lever. So I added 'Unlock' output to the 'Flashlight' trigger. If you pass through the trigger, you'll see message about flashlight, and the lever will be unlocked.

I am stuck on the second map, at the gate with the lever. Considering that there are no walkthrough videos that cover this mod, I guess that to progress to the next area without noclipping, I need to interact with the lever to open the gate. However, the lever did not move at all nor the gate would open, leaving me stuck there.