Singbird that's the other option. To have a fixed amount of xp needed to levelup and lower the xp gains for easier encounters. It's the way Final Fantasy 8 did it. Most western rpgs don't take this approach as since their inception they have been influenced by DnD rules and logic. That would be fine too, lower the xp but have a constant number needed to levelup.
Anyway, I think I need to be clearer about point 3. There are 2 arguments that I'm trying to make. The first is that players who want to maximize their experience gain shouldn't have to follow a certain "optimal" path. This may not be a problem here since there seems to be a max level of 20 (at least at the moment). Here is an example of this problem in a more general and abstract sense. Let's say you are level 1 and need 100 xp to levelup to lvl 2, 200xp to lvlup from 2 to 3 and so on. There is a level 10 troll that gives you 1000xp if you kill it when you are level 1-10 and less if you are more (cause of deminishing xp). Then let's say there are 10 orcs lvl 1 that each give 10 xp at level 1 and less as you go up the levels. For example's sake let's say that at lvl 5 they give you only 1 xp. Let's examine 2 senarios:
1st: The player kills the orcs first and then the troll. The player will get 10x10=100xp from the orcs and level up to level 2. Then if he kills the troll he'll get another 1000xp and get a few more levels. The total xp gain for the player will be 1100xp.
2nd: The player kills the troll first. He gets 1000xp and levels up to level 5 (if each levelup requires the previous level x 100xp as in the example above). Then he kills the orcs. The orcs give him 10x 1xp = 10xp. So the total xp gain is 1010xp.
As you can see for someone who wants to maximize his xp gain in a game with no respawns or level scaling, the first approach is optimal as you get 90 more xp. That may not seem like much in the current example but imagine over the course of the game how much xp can be lost that way.
The second argument is that a completionist will want to kill any enemy they can find. However if there is xp scaling the low level encounters will both be easy and only give minimal xp. Imagine fighting 100 orcs in the first level area and each one giving 10xp, even if that is not much for a high level character, as a total 1000xp may be. If due to diminishing xp they give 1xp though he'll just get 10% of the original gain. Encounters that present no challenge and give no reward are just a chore, adding nothing to the game.
