If you own a nes, you need to have Ninja Gaiden.
Like the other games Ninja Gaiden is very hard but in a fun way. The infamous stage 6-2 is what makes the game even harder with those flying godforsaken birds. Like an actual ninja you can scale up walls, pull out your katana to slice enemies, or shoot ninja stars that stick into the unlucky victim.
For a game released in 1989 in North America, it has amazing graphics and isn't ugly to look at. The cinematic cut cutscenes in this game are done very well and are fun to watch.
So if you happen to buy a nes definitely pick this game up with it.