In Inflation, when you level up, you will get a lot of Experience per kill. So much, that, most of the time, you will gain more than one level per kill. The name of the game isn't to get to a certain level, but more to get to the highest level you can before you run out of resources.
For each level, you are granted a certain number of Attribute Points (AP). These can be applied to the following categories:
HP: (Starting Value: 100, +5 per Stat Point) Hit Points.
ATK: (Starting Value: 10, +3 per Stat Point) Attack Power is the primary damage attribute.
DEF: (Starting Value: 10, +3 per Stat Point) Defense is a percentage modifier on enemy's damage. It is impossible to attain 100% Defense, regardless of how high your defense is.
AGI: (Starting Value: 5, +2 per Stat Point) Agility increases your chance to generate a combo, and to a lesser extent the ability to generate Criticals and increase the damage when you crit.
LUC: (Starting Value: 1, +1 per Stat Point) Luck is the base value to generate loot. At higher values, you generate more gold per kill, and have a higher chance to drop loot. This is modified by the level of the area, thus, a higher level area requires a higher level LUC to drop loot. LUC also increases your chance to crit. LUC also increases Crit Damage.
For all modifiers (except HP), they are modified by an enemy's Point Value, which means you need more Attribute Points to keep up with how high enemies will get.
Player Level: Player Level is attained by killing bosses. The first time you kill a boss from this list, you are given one Player Level (Called "Base Abilities" in the Character Select Screen). These are the only bosses that killing them will grant you a Player Level. Other bosses will not give you Player Levels, and killing these bosses will only net one level the first time you kill them; subsequent kills will not grant extra levels. When calculating bonuses, Player Level is combined with Character Level for a total bonus. For more information on Player Level and stats, check out Player Values.
Found in the 5200 area. After defeat; transforms the Good Lands into the Bad Lands.
Level 5: Boss (Lv25555)
Level 6: Boss (Lv36000)
Level 7: Boss (Lv37777)
Level 8: Boss (Lv41111)
Character Ability: Character Ability Level is an additive amount of bonuses that are appended as bonuses when you spend skill points. For example, if you select a North Edge (Top; ATK) Character, you will gain extra points in ATK. Note that this bonus applies to gems too - an HP+ gem on a HP character grants more points than on a pure ATK/AGI character. You gain Character Ability by finishing the game. When you finish the game, the chosen character gets 1xp per level gained. If your character hits the following thresholds, your character is granted an additional level.
Maximum Player Level is actually 16, achievable after killing all the bosses in both normal and hard mode ( excpet 93333 Boss, Tenryu).