About What is a TCG? A TCG is a trading card game that you play online. Original Concept The concept of online Trading Card Games was originally thought up by Calico. TCGs made it's debut when Calico opened the very first TCG, Senshi Card-Mania!, a TCG for the Anime, Sailor Moon. Main Event Welcome to Main Event. Main Event is an online TCG (Trading Card Game) specially designed for pro wreslting. This is a mini TCG which means it is generally based on member trading, automatic games, and freebies.