by L3nn0x on Fri Feb 22, 2019 4:52 pm
It's very dependent on the scope of the project. If you think AAA games like Skyrim or Destiny or Anthem, it's about $100M and between 200 and 300 people working on it for a couple of years. It can also be a one man project finished in one weekend.
In general for resources for RPGs (the most complex type of game you can make btw) you want assets : everything graphics, from pictures to level design, sound from background music to sound effects, gameplay and difficulty scaling. You also want a story with character design, various items, actions, enemies.
There's not much difference between PC and mobile, apart from the fact that mobiles are much more limited in terms of raw power so you'll want to tone down your graphics, change your UI to be touchscreen friendly and adapt your gameplay to be playable in short sessions.
If you don't have all of that but still want to make a RPG, try RPG Maker. It's a software that provides an absurd amount of assets and all of the framework you'll need to make a basic RPG. You'll need to be able to script in Ruby if you want to make a more personalised game, but it's a pretty good start I'd say.