Here's another timely Halloween-themed Hack idea- SRAM save feature for Zombies Ate My Neighbour! (SNES)
This one's a no-brainer; a killer classic, mired in the late-game by the limited password system. The problem is that the password encryption as it stands is limited in that it doesn't save your accumulated weapons, which makes it frustratingly difficult to continues with a late-game password, as you won't have enough ammo to finish the game.
The devs have publicly stated that they wanted to include a battery save on the cart, but due to costs they had to go with an admittedly inadequate password. Here's an excerpt from an interview with the makers of ZAMN:
"Item management is crucial to completing ZAMN, but as Ebert reveals this was more a side-effect of two other factors: "If we could have afforded the battery on the cartridge we would have saved it all for you! The password to save all the weapons you had would have been too long, so we decided that about every four levels we'd at least make it somewhat feasible that you could restart from that location. Admittedly the last few save points are very hard places to start a game from...
- Michael Ebert, game dev on ZAMN, taken from hardcoregaming101
This would be a much-needed addition to a timeless Halloween co-op classic.
I think that one guy (Draken?) who wanted to people to pay for his hacks did something just like this but has yet to release it because he wants $$$.
Don't even mention his name; he's like Beetlejuice- say it three times, and you might summon him here, but you'd regret it...