This 1991 handheld conversion of Irem‘s classic arcade game, R-Type, is surprisingly good.
Yes: it’s monochrome, and yes: the graphics are tiny, but the gameplay is spot on, which is the most important thing.
All eight levels of the arcade original are in there; the game is a reasonable challenge, and – graphically – it’s excellent, with parallax scrolling and good use of, not colour, but tone. It also has good music (written by David Whittaker apparently, although he is not credited) playing throughout.
The Nintendo Game Boy also saw a release of the sequel, R-Type II, as well. Together these two games are among the best side-scrolling shooters on the system.
R-Type was converted to the Game Boy by British developer Bits Studios.
More: R-Type on Wikipedia