I doubt anyone is currently making a new crash RPG, so I would just start kickin at it. If you sometime find out some one is making one, change it to a different one. eg. (crash rpg 3) to crash rpg 4, because the layout obviously will be different
Um... one thing about the Crash "RPG" is that it's not much of an RPG, but more of a survival map, which in the end lacks balance and creative storyline. Players either save their minerals for upgrading their highest level, or they upgraded early and became weak later on, unable to take on the incredibly strong monsters. The marine in the game is completely cheap because once you hit the marine and have a few decent upgrades, his attack speed and range and all that just makes him too powerful.
Also you can easily beat the map by having one player not chose a hero, have another player kill one supply depot, then have the civillian player walk out and gather all the discs because he is invincible.
Make a Crash map, just make it different... the current one is crap. I played it for hours with a friend, and I think I qualify to call it crap.
Give a new story line, CHANGE it from the outlook of Terran Survival, and give it some features other than "Choose your hero".