First off, I have used this engine for a week and it is great for what it is, I like it, especially noting it's free, coming from creating maps and mods on Doom with the GZDoom source port this is sadly limited.
What I'd love to see in future updates.
-sprites face multiple directions like in Doom
-lifts that move vertical, either you activate them by interacting with them or a switch
-flying enemies that are not stuck to the ground
-make some entities not bleed (robots) either bleed black or make electrical sparks
-crushing ceilings and traps like dart shooters (scripted in the make where you can enable and disable them)
-swimmable water and you can dive in it, you may change the air capacity in the map or disable it altogether
-springboards that when you step on that tile you jump high
-ladders, I'm not sure if this exists already
-doom style teleporters if they are not currently possible
-ability to change player jump height
-allies, entities that are on the players side