I worked on a small card game project for two weeks at the start of the year that I haven't touched since. (See: https://twitter.com/Bownly/status/1408954968304885764?s=20) I'd like to expand upon it for my GB Compo entry if that fits within the rules. It's potentially in a grey area between a "brand new game you barely started" and a "project you've been working on for months".

Here's a rough idea of the enhancements that I have in mind:

• Increase the unique card count from ~4 to ~10+ (the numbered cards 2-7 all function identically, so I'm counting them as 1 card for the purposes of these values)
• Improve the AI to account for the new cards/strategies
• Change the game rules from using 1 shared deck for both players, to having each player use their own deck
• Add deck building instead of the current system of using a single, static deck for every game
• Implement a progression system for card acquisition and leveling up deck capacity
• Add a (likely barebones) story/campaign (think the GBC Yu-gi-oh games if you're familiar with them)
• Add sfx/music
• Add menus
• Overhaul the existing UI/graphics and throw in some animations 
• Add 1 v 1 linked versus (time permitting)