First things first, I'll need to gather stock assets to create RPG 20XX's default asset pack. It's like an RTP except "Run Time Package (RTP)" doesn't make sense here since all required assets get built into .2xg files and players of your game won't have to go download it separately. I'm organizing what I had found before with what I can find off stock asset sites, but I think maybe the RPG creation kit that was born on RMN ought to have assets from the community.
If you have assets you're willing to contribute that have lots of "Generic RPG Energy", let me know. You'll need to license them under a creative commons license so we can all use them. Don't worry about formatting, I'll convert them, just make sure they're drawn to 16x16 pixel tile scale.
The resulting asset pack will have all of the sources cited even when attribution isn't a requirement, so be sure to let me know how you want to be credited and if there's links to something you want to include.
Anything simple and easy to map with but with an appealing retro generic RPG look is great. Here's an example I made using art I found elsewhere: