Bikkuri Software is a Japanese indie developer that specializes in shoot 'em ups. Those shmups have historically been single-player affairs, but the developer's latest game (published by Henteko Doujin) is called Revolgear Zero, and it supports 2-player local co-op. It even offers the ability to simulate co-op when playing solo in some modes! Fans of 16-bit and 32-bit shoot 'em ups will want to give this one a look.