Download an open source roguelike and get it working in an IDE.
I am hacking frogcomposband right now with shitty old Eclipse CDT IDE, and having a blast.
Mass dissolve? No pet mana cost? Never need food? Cast spells from books that are in your home and not waste inventory? Access your home from anywhere in the dungeon? Teleport towns from anywhere in the overworld? Find anything annoying? Code it away.
Remnants of the Precusors (a Master of Orion super-remake) is great too. Doomstar super-sized ships with certain tech combos? Ultralarge worlds? Mark artifacts and mineral worlds in a radius from you because you are a xenoarchaelogist? That is plain old Java so you can IntelliJ away.
Of course with any IDE there is the old breakpoint and modify values hacking, even if you don't change the code.
I want to do Cataclysm DDA next but the git clone is bombing every time. Maybe it is too big.