Making your game general

ITT we discuss how to collaboratively design our games.

There alternatives to character levels:
1,Skill-use leveling, all skills are available as level 1 and rise in levels by continued use(N*1.1^L per level) uses. Its intuitive but very tiresome to gain levels vs character leveling.
2.Upgrades from consumables: character stats are boosted by consuming some stuff that permanently alters stuff.
3.Skill upgrades from items:like reading a book in Diablo1 boost a skill by one level.
4.Skill-use gated experience: basically you're leveling up a skill instead of character(expirience goes to skill exp). Doesn't work well with non-attack skills or utility skills.
5.Time-gated item-level expirience: like in EVE online, your equipment gains levels by just existing/being alive/being equipped. Most boring and least interactive option.
6.Consumable-Experience: expirience(gain) exists but levels don't, just all skills consume gained expirience points, like mana for spells. Hard to balance for lower levels(it needs a boost for beginners)
7.Skill-use component upgrades: like #1, but instead of adding levels to a skill, you upgrade a level of component of a skill, like adding +1 range/+5 damage/+1 speed to fireball(i.e. upgrading stat components of skills by skill-level-points). Far more build diversity overall than any other option.
8.Consumable skill component upgrades:same as #7 but you need to find magic reagents to upgrade your skill components.
9.Charging skills: skills upgrade their stats by charging(continous usage) and lose with idle time. It can be combined with other systems.
Basically character levels can be replaced, if skills/stats are upgraded somehow by player.