In a card game, the idea of distance isn't really applicable. So if they were both damage dealers then they would be pretty much identical. In the end, I decided to make the Heavy a defensive class (please don't kill me).
During his turn, the Heavy can attack like any other class and, like other classes, attacking causes him to tap (Tapping is a card game term for placing a card on it's side, indicating that it can no longer be used until it is untapped at the start of that players next turn). However, if the Heavy isn't tapped at the end of that players turn, then he becomes really useful.
Whenever an opponent taps one of his character cards during his own turn, the Heavy can attack that character, provided the Heavy isn't tapped. This causes the opponent to make sure everything they do is definitely worth doing. But wait, it gets better! Because of his wondrous spinning chamber, attacking in this way doesn't tap the Heavy! So if the opponent then taps another character, the Heavy can fire again! Of course, this still uses up ammo, so eventually the Heavy will have to stop, awww... This regulates a player's ammo usage, while at the same time allowing them to use up any remaining ammo for the turn without the player feeling it has been wasted.
Example Heavy cards:
- Get Behind Me Doctor! - Allows the Heavy to take damage instead of a Medic.
- Makin' Bacon - Allows you to search your deck for a Heavy and put him into play.
- Slow Mover (Nemesis card) - Causes your opponent to double-tap (causing him to wait two turns before he can be used again).