Some ideas for current themes. I hope you will like them.

• Some assembly required - player has to compile the game themselves (on hard difficulty build instructions are not included)
• Playing both sides - you are your own enemy, which means you have to hit yourself from time to time
• Fragile - there is 20% chance the game will crash on any user input
• Color is a mechanic - you play as a car mechanic and his name is Color
• One use only - you have to complete the game on first play
• Replication - everything you touch replicates until the game runs out of memory and crashes
• Automation - game that plays itself, no user input required
• Delay the inevitable - there is no win condition and game never ends, but player doesn't know it
• Overflow - create a game that has buffer overflow and crashes
• Echoes - Echocardiograms - a doctor simulator
• Leave something behind - retire from Ludum Dare and become a farmer
• A faithful companion - a game about companion cube from Portal, but try not to get sued by Valve