Undo/Redo is actually super complex to make, it would basically involve keeping track of EVERY action the player does (spawning, triggering, all the text fields, etc, etc.) Probably not going to happen. The next best thing is probably Quicksaving (Default hotkey: C) every now and then so you can load if you accidentally mess something up.
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 "Mutilate-a-Doll 2"){kind=icon}
 "Just Chatting"){kind=icon}
 "Gravitee Wars Online"){kind=icon}
 "Pixel Twins"){kind=icon}
 "Reactor Incremental"){kind=icon}
 "Anti-Idle: The Game"){kind=icon}
Undo/Redo is actually super complex to make, it would basically involve keeping track of EVERY action the player does (spawning, triggering, all the text fields, etc, etc.) Probably not going to happen. The next best thing is probably Quicksaving (Default hotkey: C) every now and then so you can load if you accidentally mess something up.