So.. This is my first LD attempt and my strategy is to go with the first idea that pops to mind, so the winner is:

• Enemy: Sleep (maybe sheeps?)
• Weapon: Coffee
• Hero: Tired programmer

Tools:

• Game Maker Studio
• paint.net / inkscape
• Bfxr
• Jukedeck / Magix music maker

Edit: Here’s the background music I generated for the game with Jukedeck: