Alternate Systems could include
- Incremental Leveling [same as above, mostly, except increases happen along differing linear paths. ]
- Advancement through Failure [Hard to advance something you're already good at... without pushing yourself beyond your existing capacity.]
- Ongoing Point-Buy [ As incremental BUT the player chooses which path is 'paid for' first.]
- Advancement as Currency [A subset of the point-buy system - this adds a layer of decision-making for the player, since they can either have the immediate payoff of spending a point in-game, or the quick payoff of spending the point on some small incremental advancement, or the delayed gratification of saving up for a powerful ability.]
- Advancement by Use [systems take a bit more tracking than the ones above, but you don’t have to worry as much about pricing abilities or tuning the leveling system... the challenge being player ability-spamming - the use of every conceivable skill all of the time.]
- Milestones [ The milestone could grant a level, or merit points, or a milestone could even be when the players have used a certain number of abilities in-game]
- Adjustment rather than Advancement [In this system, the character doesn't actually advance... they evolve becoming more adjusted to the immediate requirements of the story at hand... but not necessarily more capable. ]
While I'm certain there are other ways to reward players... my systems utilize a few of these... specifically, the 'Standard XP', but also 'Advancement by failure', 'Milestone', and 'Advancement as Currency'.