the TMNT Rpg from Palladium games is a unique beast for me. On one hand I love TMNT on the other hand I am not a big fan of the Palladium game engine. this is one of only two Palladium games I have bought with my own money. the other one is the Macross II rpg. Now this RPG does fix a few of the issue I had with the rifts take on the Palladium game engine. there is virtually no Mega damage nor mega defense. I think things like rocket launchers and tanks use them, but as those are not common in the game Mega does appear often. the second is there are no Classes per say in this game. instead every animal is given a set number of build points called bio points iirc to give themselves different levels of mutations. as for skills that depends on how you were raised and how you got your mutations. so a random animal exposed to radiation and living in the woods will have a different skill set then a precisely engineered mutant raised in a think tank.
another cool aspect of the game is team building. in team building the entire team gains bonuses to stats and skills based on what the other members of the team have. the only downside is everyone has to be the same animal and have the same origin.
sadly the game line came to an end due to ironically the popularity of the TMNT cartoon franchise. You see this game was based on the original comics which were much darker and serious then the cartoon. with the cartoon becoming popular no one could take the serious tone of this RPG well seriously. this drop in sales of the book resulted in Palladium dropping the product line. though I have heard that most of the concepts survived and become the after the bomb RPG.
A note of caution the TMNT RPG has had a few print runs and one of them has a very out of date chart on mental illness like most early Palladium games had. this chart that uses the DSM-3 or maybe DSM-2 has Homosexuality listed as a mental illness. this means that if used you could get beat up so bad you turn gay.. yeah if you find a copy of the book with this chart it is best to ignore it completely.
somewhat recently Ivan Van Norman of geek and sundry did a multi part session of the TMNT RPG, but he used a homebrewed system that made the game more playable. http://geekandsundry.com/shows/no-survivors/ .