The tags Trading card and Card game were some of the most frequently mistagged tags out there.
Currently, the tag "Trading card" is used for card art (with over half of the posts with this tag were High School DxD card arts), but these tags were often interchangably used with "Card game" tag for the depiction of a physical trading card game (TCG) in the post (such as Yu-Gi-Oh! for example) with one tag replace the other.
On the other hand, the tag "Card game" seems to be used to refers to depiction of character(s) actually play a game using cards, but these tags were also applied to a post featuring the TCG card not being played or just simply being held by the character. Also, the tag seems to be frequently mistagged, since there are a handful of posts featuring character holding playing cards but not actually play them.
Since not all trading cards are card games, and not all card games are trading cards, I think we need a proper definition on both tag's usage.