Tiny Zombies are much faster than Normal Zombies and much smaller. Their size make them harder to hit, making Tiny Zombies a dangerous foe. Originally, the Tiny Zombies spawned in the Colosseum after a player retrieved the Military Sniper.
The Tiny Zombie will try to get in close and deal constant damage to the player, making counterattacks difficult.
Using melee weapons is a good idea to preserve ammunition and prevent the Tiny Zombies from dealing too much damage to you, or trying to get high ground and escape their reach and snipe them from there.
Tiny Zombies are likely a zombie variant of the halflings unit in TABS.