Iron Doors: remake wooden doors sprite to iron doors, more durable, instead of 3 plank/1iron ingot costs 6 iron ingots.
Stun trap: remake bear trap sprite by adding tiny blue crystal inside, when enemies are near (e.g. 3x3x3 blocks with trap inside) they're stunned for few seconds and player needs to reload it with crystal to make it work again, instead of 1 iron ingot costs 1 iron ingot and pylon ward*
New bomb for alchemist: remake colour of old bomb , make it more effective against corruptrons/bricktrons and less effective against walls, instead of 15 brimstone costs 5 brimstone and 10 iron
Make official co-op invasion mod with different crystal for each player or 2 factions of bricktrons on one crystal (so we don't have to rely on buggy mods)
New type of stairs: corner stairs 1x1 just like merlon corner.
Wooden walls: they can work like beams (auto connecting to wood columns) but they cover the whole block with wood (not only the middle because they look like fences).
Regrow or plant trees: use 10 brimstone* on a trunk to start a process of regrowing (e.g. after 2mins tree pop outs) or use 10 brimstone* on ground to plant a tree (takes more time than regrowing), everything available via build menu.
* add blue crystals back in to the game only under the ground (less common than iron/brimstone) and use it in stun trap or to regrow/plant trees