Double Action Blaster Guys by NovaSquirrel is a single player action game but also allows two simultaneous players. DABG for the Nintendo Entertainment System / Famicom is a sequel to “Forehead Block Guy“.

NovaSquirrel provided the following updates on his game:

*Changed to NROM-256 with CHR RAM, decompressed at the start before the title
*Revamped menu system (and the editor asks for confirmation to quit now)
*Versus modes with powerups
*More levels to use new blocks and enemies
*Levels can scroll
*New blocks: Bombs that go off every 4 seconds, tiles and platforms that toggle between solid or not every 4 seconds, switch to instantly toggle all toggleable blocks, moving springs and moving hazards, teleporters, insta-kill spikes, tiles that cause a bomb to drop above you when you walk through them
*New enemies: rolling and jumpy balls, enemies that shoot aimed at the player, Thwomp clones, a flapping owl, a potion and an enemy that continually shoots right
*Various bugfixes and minor changes

http://forums.nesdev.com/viewtopic.php?f=22&t=10325