I’m in. Here’s an idea for every round 1/2 theme!
Why wait until the theme is announced when I can just come up with an idea for each now?
Anyways, I decided it’d be a fun exercise to come up with an idea for every theme, so here they are:
Afterlife – Instead of respawning, when your player dies you just go to hell and play that
Against the Rules – Wizard table tennis battle, anything goes
Alternative Physics – A universe where if anything stops moving, it ceases to exist. More movement = more existence
Ancient Ruins – Game starts, you take the gold statue (or whatever) and all the walls are constantly closing in on you. Escape
Apocalypse – The apocalypse occurs, unrelated to the game’s story, in the very middle and you can never stop it and can never finish the game
Chaos – Every possible action you do in the game causes a chain effect of consequences, making it insanely difficult to predict/finish
Colony – Stealth game, play as an ant ninja who must sneak into enemy colony’s nest and assassinate their queen
Dreams – Dream version of a human has “dreams” where things are just normal, 2-phase gameplay of some sort
Electricity – Your character emits constant charge, touching conductive things transfers the power, use this to beat levels/enemies
Everyone Is Dead – You play a Wall-E style robot, but instead of junk, your job is to clean up piles of dead bodies
Flammable – You are on fire, water lies over yonder, many things stand in your way, get there fast!
Going Backwards – Hero’s journey in reverse
Industrial – The piston yard, a giant mechanical factory of pistons everywhere, don’t get crushed
Journey – All you have to do is cross the rickety bridge, who knows what kind of challenges you’ll face?
Keeping Control – A side view flying game, reach the most ridiculous speeds possible, hitting walls sends you spinning+bouncing, try to recover!
Lifecycle – You are a video game baddy mom, and you must raise+feed your children. Don’t be seen by the heroes or they’ll kill you/your babies!
Lost – Leave your home, find an item, as soon as you get the item, the lights go out, and the path you took before is the most dangerous way back.
Mutation – Wacky roguelike with randomly generated “quirks” every game (eg. every 4th turn you step to the right, gold poisons you, etc.)
No Weapons Allowed – Sneak your way in unarmed, find treasure, massacre your way out with it, treasure is randomized
Point of No Return – Everything you do/touch can only be done/touched once, or you die
Rediscovery – A 4×4 set of rooms that are occasionally/randomly changing, but you have a set of objectives to accomplish
Rise and Fall – Build a futuristic city as fast as you can w/ twitch gameplay, then destroy it w/ apocalyptic powers for a high score
Seasons – You are a spice dealer collecting goods, as you gather more, you go through “transitions” of exposure to the drug, causing powers/problems
Surrounded – Super hardcore ambush survival, you have only one weak attack, and each single enemy is significantly more powerful than you. How far can you get?
Underworld – Control two characters at once, one on the upside, one on the downside. The worlds are mostly the same, but some things vary.
After the End of the World – You are the super villain, and you just won! Now what do you do with your time?
A Man Alone – Try to find a peaceful place to meditate, but everywhere you go, some people/creatures always interrupt you!
Amnesia / Limited Memory – Pseudo RPG game, but your experience points are constantly draining, you have to fight to keep leveling up
Beneath the Surface – Stealth game where you can phase into walls, but if you stay in a wall too long you’ll get stuck there forever!
Desperation – You’re falling to your doom, hit as many things on the way down as you can to break your fall! The less bones broken, the better.
Dimensions – Everything is paper flat, but only visible from its front-side, and can be facing 4 possible directions. Switch directions to find your way.
Distortion – The entire land is shifting, all objects do something based on their distance from you or what axis you’re moving on.
Ecosystem – Keep an ecosystem of mini people+plants alive for as long as possible, high scores should be able to reach days/weeks/months!
Erosion – Use your laser to dig through the ground and escape, but the ground is constantly growing back, and may try to fight back!
Experiments – Help the experiment subject get through the rooms as the scientist w/ control panels that control it!
Forgotten Places – Platformer w/ a series of levels, each with an end, but every level has a “secret” end. Find only the secret ends to truly win!
From the Inside – Defense game inside a monster’s brain, punching enemies around. Hitting parts of his brain makes his body on the other screen dance.
Minimalism – A series of one-screen platformer levels, but you can only play by hearing, because only the first frame will ever be shown.
One Shot – Simple, short game, you VS a single very challenging and complex boss fight. Beat him.
One Way Out – Escape from the exploding core using your magnificent spaceship-flying manoeuvres through the winding passageways! Top-down style.
Out of Time – Challenging platformer, you only have 2-5 seconds to get each timer, or you die. Sometimes they are placed in tricky spots!
Perspective – You are the engineer of a space battleship, keep the ship running during shaky space battles, you never really know what’s going on.
Potato – You’re a butch she-warrior nicknamed Potato Face who has been cast into the coliseum, survive in the face of the laughing, taunting masses.
Regeneration – You revive if you touch the red platforms, but you can’t always reach them. Die in ways that your ragdoll can land correctly on them.
Replication – You’re in a machine and have to perform actions on the spot, every N-seconds, a copy is made that performs those actions in the actual level.
Side Effects – A shooting game, get though the level killing enemies. But every enemy you kill has a randomized and strange side effect in the level.
Space – You’re stuck inside a tiny square room amidst total blackness, unsure how you got there. How can you even escape?
Stuck Together – Two people stuck back-to-back, one can climb, the other shoots a gun. You can turn them around, get through the level.
Survive – Naked bearded man stranded in the desert, find where the sword & shield are located before the sand colossus arrives to claim you!
Teamwork – Simple platformer or puzzle game where the player is meant to be blindfolded and instructed by a friend’s voice, friend gets the headphones though!
Some are shitty, some are pretty good, others don’t even seem to match the theme they’re for. But I don’t care, it was fun! 
Excited for this Ludum Dare, I’ll be doing the 72-hour jam with an art collaborator this time, and want to make something really small and insanely polished!
Which is your favorite of these? 