Experience

each level up gives 1 skill point upgrade and 1 passive stat point to allocate
 * level 2 = 300 xp goal
 * each other level thereafter = last xp goal + 100
 * (e.g. lvl 3 is 300 + 100 = 400 xp goal and level 4 is 400 + 100 = 500 xp goal)