R-TYPE / Irem / Turbografx 16
R-Type copies a lot of its elements from Gradius, most notably the visual style, but its most memorable feature is that you basically have to memorize the layout of every level to survive. This involves a lot of dying, starting over, etc. Some people enjoy this sort of thing. Others don't. You probably don't need any further input from me to know where you stand. Only one other point of note - the North American and European Virtual Console releases get the full 8 levels of this game, while the Japanese get it split into two separate games with four levels each (since that's they way it was originally released over there).
* Gameplay Video