What other neat places are there?

Hint 1 of 11:

(1) At the beginning of the level, there's a switch that you can hit to lower
the electric chair, revealing some stuff.

Hint 2 of 11:

(2) One really cool place is near the beginning, in the chapel.

Hint 3 of 11:

Go up to that weird picture-like thing near the windows, and press the Space
Bar.

Hint 4 of 11:

Everything should turn red.

Hint 5 of 11:

Go in, and you'll not only find a Chaingun, but you'll find the Space Marine
from DOOM!

Hint 6 of 11:

(3) Also in the church, go to the back, and stand between the two doors.

Hint 7 of 11:

Shoot at the door above the altar.

Hint 8 of 11:

The platform will raise, which will not only allow you to get an Atomic
Health, but you'll also find a monk from Rise of the Triad, hanging on the
ceiling!

Hint 9 of 11:

(4) Also, check out the cell next to the chapel.

Hint 10 of 11:

Behind the bed is a secret passage.

Hint 11 of 11:

Check out another hidden passage near the floor on the cell.