I think I've figured out what I'm going to do for a progression system in VizionEck.What about loot boxes?
1. Play the game and gain experience. This experience can be spent as an in game currency to unlock new maps, new modes, and new titles. Outside of costing xp, these may also have other requirements to make them more interesting and unique such as needing to have at least 10 kills in a row to get a killstreak title.
2. Experience also works towards increasing your level. Every time you level up, you earn a "development coin" which at that moment you spend on one of five potential new features. It's basically like an in game poll to decide what people want the most and once features get enough coins they're developed. XP can be spent on development coins as well.