Neutral jumps, even though there is no climbing stamina, I still want to climb walls in the funny way, it was the first tech I tried.
A setting to toggle camera lagging. Most notably on keyboard, if you walk to left or right of you camera view (like a side scroller game, NOT towards or away from cam.) the camera will lag behind your movement and problematically turn to face where you are going, which prevents keyboard players from walking in a straight line. This is very painful in some cassette rooms (behind the sign, spike rings one) and tight walks, where you are forced to look behind or in front, which are otherwise very bad angles for depth perception in those cases.
A golden strawberry, because pain and suffering are shiny and golden.
The ability to put theo in a crystal, and carry him around. That way I can theo climb, because it's funny. (Also, bring him into the cassettes.) Ik this one would be hard to implement.
An option to turn stamina limits on, because then neutral jumps would be useful.
Play as Baddy, maybe with special dialogue.