Things I would suggest:
- Key rebinding
- When using echo, surrounding geometry should still be visible for a bit (or decay as you move). It can become very disorienting being in constant darkness, which causes you to have to echo more than normal
- Toggle to hide in lockers instead of having to hold F
- Severely dampen how far echo travels through walls. Currently, if you're in a room and there is a room next to it, enemies in the other room can still hear you if you use echo