One of the best games I've seen in the past month!

Yes, it could use some graphics, but this game is absolutely brilliant!

Super fun, with a lot of replay enjoyment.

Besides graphics, it would be nice to see some task specific skills improve.
For example:
when you race, have a skill that goes up each time to improve future racing.
When you win at darts, improve your darts skill.
These skills could be hidden if you like.
It might also require that you limit the number of attempts / opponents at various locations to prevent leveling too fast.

If you add graphics, you could have more than one bar to play darts in.
Darts could be done in leagues, and you could move up after each dart season.
Actual dart matches for some leagues are done in 3 types:
2 games of 3 on 3, 3 games of 2 on 2, 6 games of 1 on 1.
This would allow you to play up to 3 games per "game day".
You would then participate in the 3v3
If you're one of the top 2 in your match, or your team wins: you get to play 1 of the 2 vs 2 also.
If you do well in the first 2, you get to play one of the 1 vs 1.

This would allow you to play a mini game within the game where you try to hit locations on a dart board.
Move your cursor to show where you're aiming, then click to throw.
Ability to hit would depend mostly on Dex + Wit, but a little on Str.

Similar could be done with checkers, where you play in a tournament, and you can see how you're progressing, as well as how others are.
Use either single elimination, or maybe a binary system, where you play a set number of matches until all the competitors are ranked.

Just some ideas.