how about something like pokemon, bakugan evolve at lvl 10 and gain experience by the 100's depending on how much you win by. exp: if you win by 100, you get 1000 experiencebasic-no experience1-100 exp2-200 exp3-300 exp4-400 exp5-500 exp6-600 exp7-700 exp8-800 exp9-900 exp10-1000 exp(once you gain a lvl, you have to add the experience, like lvl 1 + lvl 2= experience 300)