Mega Drive hacks I'd like to play:
Landstalker - There's a handy shadow when jumping, and you don't hit walls instead of enemies in cramped spaces any more. You also can no longer button mash key enemies to death, because their AI is now pretty good. Bubble enemies no longer scream when killed. The inventory is slightly larger now, and colours have brightened, pleasing the eyes of the player.
Kid Chameleon - Cheap hits/kills are fewer. Movement control is somewhat tighter, down-thrusting blocks is easier, and hover board controls are less sensitive. You no longer get crushed from destructible (by touch) blocks if you ride into them on an elevator. If you pick up a helmet while another helmet is dropping from a block, the other helmet no longer disappears. The placement of items is changed in a way that makes getting to them always feel worth it. Finally, there's an easy to use level editor (it's in the works IIRC), and an option to play as Alex Kidd (lol).
Atomic Runner - You can now adjust your jump height and run to the left. Alternate weapons have been added where the homing missiles used to screw you over. Somersault controls are changed so that they are activated by pressing jump again while in the air.
The Lost Vikings - There's a Kaillera mode where players have their own screens, and the game is faster paced overall. The Amiga music has been carefully ported over and inserted where it fits, and there are no annoying sound effects. Enemies can no longer shoot from off screen, and the Vikings can look up and down for hazards, like Sonic. Items carry over to the next stage, and there's a checkpoint power up which is rare but oh so useful. The hit detection is perfect.
King Colossus - There's less dead space, game difficulty and weapons are better balanced (bombs can now be used as weapons btw), and your melee attack is a bit faster. The hit detection is perfect. Herbs are no longer auto-used should you be carrying one when finding a new one. You now get to keep the death scythe after the gladiator battles along with the other weapons. Even the colour palette has been touched up in places.
The Story of Thor/Beyond Oasis - Both the scrolling and the hit detection are tighter, and cheap hits are minimized. The six button controller is used better, making combos easier to pull of so you'll want to keep using them. The soundtrack and sfx are less grating, and someone wrote a more upbeat and adventurous tune for the overworld, as well as new, exciting boss music. Running around is less clunky - you can change directions and breaking is quicker. Getting knocked over is less of a hassle. There are no areas where it looks like you can exit in spots where you can't. Silver Armlet and the Wizard before the plant elemental are no longer pushovers.
Eliminate Down - The sound engine is reworked with care, making everything sound as good as in TFIV. Checkpoints stay after losing a credit OR your weapon is only downgraded one step after losing a life (which feature you want can be chosen in the options menu). No more safe spots.
Adventures of Batman & Robin - There's an easy mode which isn't as repetitive and where enemies take fewer hits to kill. Targeting controls are now perfectly responsive and can be switched on the fly like in Contra: HC. No more checkpoints where you can't re-power up your weapon.
Pulseman - You can control the voltecher power better by moving in one of four different directions on activation (still defaulting to diagonally upwards), and the dash move is less clunky to use (either mapped to its own button via six button controls or to a more comfortable combination like down+jump) while running is set to double tap or its own button (because auto-run after a few steps is crap for this game). The delay after dashing is shortened, as is the invincibility time on the jump kick so that bosses can actually hurt you in-between the kicks, hopefully forcing you to dash away instead. The hit detection around spikes now works properly. Enemies are more interesting, and there are more of them where previously there were none or very few. There's no slowdown from charged shots any more. You no longer lose the voltecher power up item when moving between sub areas of a level, getting punished for no reason. You can look up and down like Sonic, preventing some blind jumps. In the bonus level there's a notifier showing where the paddle is when Pulseman moves away from it, making it more playable. The autoscrolling level is more fun.
Monster World IV - It has momentum based jumps, and running (now mapped to a button instead of double-tap) is no longer canceled when transitioning between screens. MWIII equipment mechanics are back, and most of the bosses are harder. Returning to beaten areas is now possible. Shion is an unlockable character. Pre-dungeon levels are slightly longer and more intricate, while the ice palace has been made less tedious.
X-Men 2 - Adds a Kaillera mode where each player has their own screen. Players get to pick two characters to switch between during a mission OR a mission can be restarted with a different character (leaving the current character damaged until the next mission so you can't abuse it). The scrolling is tighter and everyone can look up and down like in Sonic. Characters are better balanced; Gambit is no longer taller than others when ducking and has a higher rate of fire than Cyclops. Characters can move while crouching. Magneto can hover (slowly) left and right and has better jump controls. In single player, no enemy can take up to 4 normal attacks but only 1 attack att full HP. Stage 2 is shorter but has slightly tougher enemies. Enemies can't shoot from off screen, and smaller projectiles can be blocked. An easy mode has been added with a few more checkpoints within levels, a few extra starting lives, and more 1-ups to find. No safe spots on bosses. Better hit detection when shooting enemies and around the exploding plants in the jungle. Jungle area is also a bit more open now. Annoying sound effects and instruments have been improved.
Aladdin - Fully playable Abu. The scrolling stays tight when jumping. Slashing while running won't cancel if you let go of the d-pad during the attack (same thing used to happen when landing from a jump - no more). Improved instrument quality for the music.
Wonder Boy in Monster World - Shion's initial movement speed has been bumped up a bit, his jump height can be adjusted, and he can attack up- and downwards (some enemies and areas have been altered to make this useful). There's a new boss in the underwater palace, and the final boss has been adjusted to somewhere in between the western and Japanese version in difficulty. Shield magic is now useful, while Thunder and Power magic has been weakened. The game overall is harder, longer and more varied, with some new creatures and music inserted from Monster Lair.
Quackshot - Donald moves a bit faster, and there are new platforming puzzles inspired by the indie game Fishbane. You no longer need to backtrack out of the temple in Mexico. The sound engine has been redone as well, further pleasuring the ears.
Mega Man: The Wily Wars - The movement controls are just like in MM3 NES now, and someone collaborated with LegendofRenegade to insert his music remixes into the game as faithfully as possible. You can pause while your bullets are on screen, although it does remove the bullets, and MM doesn't let go of ladders when you pause should he be holding onto one. The slowdown has been removed.
Contra: Hard Corps - Levels are slightly longer, the tedious tunnel boss fight is no longer tedious, and sliding is now consistent when on land and on water.
Dynamite Headdy - Bonus levels are fun now, the Stair Wars boss is pretty quick, and boss HP always feels just about right.
The Revenge of Shinobi - Joe can look up/down, and no longer goes auto-melee when standing above item crates/next to the metal lifts in the factory level/next to the doors in level 1. Knockback is consistent. There's no delay on throwing right after jumping. There's a neat toggle in the options menu between Shinobi 3-style somersault and original style. The original Joe has been added to the game as a playable character, though I'm not sure he can actually beat the game with the powers he has, but hey that's still pretty cool.
Ristar - The speed power up from the GG game has been inserted into the game, the traps on the fire planet work as intended, and the hit detection is perfect. Somehow the voice samples are cleaner as well.
Panorama Cotton - There's a Sega CD port, which is silky smooth and sounds amazing. There's also an option to make Cotton transparent if you're having a hard time seeing what's going on at any point.
Langrisser II - The difficulty scales better so the game doesn't become too easy near the end if you've played perfectly, and summons are worth it. The sound test works like in the first game. It's much harder to put the final boss to sleep now, perhaps impossible?!
Gunstar Heroes - You can now switch targeting controls on the fly, like in Contra: HC.
Rocket Knight Adventures - You can control the length of the rocket boost, and the easier autoscrolling sections have received an increase in difficulty.
Shinobi 3 - The horseback and surfing levels are noticeably harder on higher difficulty modes, climbing the ceiling is slightly faster, and there's a new double plane segment reminiscent of the previous games.