Great work as usual !
Never played tempest but I know this is a famous vector game.
I suggest you use a 21" PC monitor capable of 1600x1200 : this will make the game look like on original vector monitor.
Some ideas of other classics of all time for your next builds : q*bert, karate champ (data east), kung-fu master, gouls'n ghosts, ghosts'n goblins, street fighter II, marble madness, rolling thunder, shinobi, dragon's lair (lol), out run (this one should be difficult), etc...