OutZone is a pretty awesome vertical run-n'-gun by Toaplan, and the best in the genre I've played so far.
I've gotten as far as the Stage 2 boss, and up to that point bullet density is surprisingly thick and your hitbox is wide. Twitch reflexes are quite necessary, and failing to shoot quickly and accurately may kill you before the bullets do.
You have two weapons, which you can change at frequently-placed item boxes. The first of which is a rapid-firing laser that aims the direction you're facing, and as you're trying to dodge and shoot at the same time it's RATHER DIFFICULT to hit anything. This is why I generally prefer the second weapon, which is a forward-firing spread shot. As it's forward firing, you can concentrate more on the bullets -- However, you are very vulnerable to enemies approaching from the side or (rarely) behind.
When you get Game Over, it tells you what percentage of the game you've completed. This is a neat feature. So far I've gotten to 18% on one credit, so this game's probably going to last me quite a while.
If you're too lazy to emulate it in MAME or just want a sneak preview, have a pro spoil it for you.
Arcade Longplay [151] OutZone