Great idea! 
Here's how I would do it. Feel free to disregard this advice.
- Incremented levels (e.g. Level 1 = 100xp, Level 2 = 250xp, Level 3 = 500xp).
- Level-based bonuses. Your pictures are a good idea. It'd be cool if the pictures started out with noob culture like Naruto and geisha and then progressed into shamisen players and obscure 17th century poets.
- +1xp per incorrect answer, +2xp per correct answer, -1xp per due card (so that your level will gradually drain if you avoid reviews).
- Some kind of combo bonus (e.g. +10xp for five correct answers in a row).
I think anything more than this risks being counter-intuitive. Giving more xp for 'Easy' vs 'Good' or 'Hard' will only encourage inaccurate responses imo.
Anyway, fantastic idea, good luck developing it further.
Here's how I would do it. Feel free to disregard this advice.
- Incremented levels (e.g. Level 1 = 100xp, Level 2 = 250xp, Level 3 = 500xp).
- Level-based bonuses. Your pictures are a good idea. It'd be cool if the pictures started out with noob culture like Naruto and geisha and then progressed into shamisen players and obscure 17th century poets.
- +1xp per incorrect answer, +2xp per correct answer, -1xp per due card (so that your level will gradually drain if you avoid reviews).
- Some kind of combo bonus (e.g. +10xp for five correct answers in a row).
I think anything more than this risks being counter-intuitive. Giving more xp for 'Easy' vs 'Good' or 'Hard' will only encourage inaccurate responses imo.
Anyway, fantastic idea, good luck developing it further.