Are you familiar with RPG Maker? If you are, you can use that to create your own role-playing game based on what you want it to appear. You can make use of their templates, music, graphics and other materials there for free if you apply for their trial version. However, some resources there would require you to purchase, so better be ready to have money reserved for that.
Once you've chosen and purchased what you need for your game, you can then proceed to incorporate it using the tutorials they provided. Here are some nice looking graphics for characters you might want to check out. I have included the prices and links of each of them below so you know how much they cost and where to get them.
RPG Maker MV: Cover Art Characters Pack
Price: $9.99
RPG Maker DS Resource Pack
Price: $29.99
RPG Maker DS+ Resource Pack
Price: $14.99
Now if you want to know where to use Bitcoin in the game, you can consolidate it as a reward for killing monsters or enemies. For example, let's say one killed a monster at a certain level, that character will earn satoshi based on what the rank of the monster he killed. If one ended up killing a rank 1 monster, he earns 1-10 satoshis for it. In addition, you can also incorporate Bitcoin when buying and selling premium items. The rarer the item, the higher the price of it in bitcoins.
Hopefully, you understand where I'm getting at here.