1. Character
1.1. Stats
1.1.1. HP
1.1.2. Stamina
1.1.3. Aim
1.1.4. Luck
1.2. Level progression
1.2.1. array containing exp treshholds for different levels
1.2.2. each levelup grants f.example 6 points to allocate on stats
1.3. Combat:
1.3.1. Melee
1.3.1.1. Mouse1 for attack, limited by stamina
1.3.1.2. Mouse2 block?
1.3.2. Ranged
1.3.2.1. Mouse1 for attack, limited stamina
1.4. Pickup loot:
1.4.1. Walk over! simple hit collision
2. Inventory
2.1. Simple inventory list, dont waste time on a grid
2.2. equipped item highlighted by icon or the frame
2.2.1. make sure only 1 weapon is equipped at a time, auto switch when equipping new
3. Graphics
3.1. Sidescroller
3.1.1. Think terraria, might require sprite animation
3.2. topdown
3.2.1. think realm of the mad god, no animation really needed
4. Enemies
4.1. Melee enemies
4.1.1. make some that uses the weapon types you have, try to find a way of making them share their attack code with the player
4.2. ranged enemies
4.2.1. same as with melee enemies just with the range
4.3. drop loot
4.3.1. random drop based on character level
5. Bonus content
5.1. NPC interactions
5.1.1. this is not required to have a proof of concept for your RPG, but a nice extra thing to have