The thing is, some systems already kind of exist - if feels like the coding is 40% to 80% already there (which relates back to another basic concept, using two-plankers). Of course I don't *know* that as an arm chair dev, but I do see what's already in the game.
To give an kind of examples here dips into specific suggestions a bit, but they can be fleshed out more fully later. Maybe.
Making lizard racing a game:
simpler - race against NPCs in different locations for wagers of gold
more complex - raise/train your own lizards to race against other players
Allow us to play spike ball:
- simpler - race against NPCs (you already do for a quest) to win prize money
- more complex - race against NPCs and other players to win prize money
Bare-handed tavern fights which could include some or all of the following:
- fight for reputation and achievements for gold and reputation
- bonus for fighting drunk (we have drunk animations and could add fighting/movement penalties)
- have special NPCs that sometimes spawn as part of achievements
- questline(s) for the sparring circuit
I could go on and on but maybe this gives an idea of what I mean?