vocal vector
Basically, don't have any of the customization options be locked behind robux. Limiting the player's freedom of expression behind a paywall of any kind, no matter how small it may be, makes the player feel extremely trapped in the character they got instead of the character they wanted.
Examples of this would be things like eye color, hair color, maybe for demons it would be horn types, maybe for slayers it would be nichirin blades, whatever it may be. Even lootboxes are fine as long as it uses the in-game currency instead of robux. Other ways to lock cosmetic items from spawn access would be bosses that you have to kill somewhere mid-game to unlock. Maybe you could have a boss that has multiple blood masks that will change the moveset of the boss when the mask switches, and if you kill the boss while it's on one mask there's a chance that you can wear the mask FROM the boss. That's just 1 way to make cosmetics fun to obtain and make sense in-game
soft flax
runic maple