Marvel Universe Game
Slewis, there are no playable races. The game is entirely centered around creating your character using points, and you have Attributes, Actions, and Modifiers. Your Attributes are basically stats, and everyone has the same ones. Your Actions are unique to you, so if you want to make a symbiote, just take Actions like Shapechange, Wall-Crawling, and Web-Slinging, and take Modifiers like Danger Sense. Maybe apply a Weakness to Sonic and Fire attacks to your Durability Attribute. Easy as pie.
You have so much of my attention right now, CrazyUncleZed, I wish I could describe how this post makes me feel. There is a conflict, but in the end, sign me up. XD