My Motorola pager was buzzing like crazy,
@Shifty
Lots of fun games listed so far.
Current favorite is Dodonpachi Daioujou, often shortened to DOJ or DOJWL. I've talked about it elsewhere on the site so I won't go into too much detail here.
This particular game's claim to fame is that it was so difficult that the top players in Japan asked CAVE to tone it down, which resulted in a different title called DOJ Black Label.
Scoring begins when you can chain a full level. The difficulty, of course, is that you only have a 1 second window (or a half-second, depending on which enemy you killed) before your Chain meter depletes. You must either kill another enemy or your chain drops. This is too much to consider on the fly. Players practice a route allowing them to kill enemies fast enough to keep the total number of bullets down, but not
too fast as to not drop their chain.
The Hypers make things quite a bit crazier: your Hit counter is multiplied when in Hyper mode, but the speed of bullets increases, too.
It's not really a complicated game in the sense that your objective is simple: use your Hypers in areas with dense concentrations of enemies, don't use Bombs (massive bonus at the end of the game), don't drop your chain, and don't die. Simple!
Here is a 2-ALL of the game. It's a useful video for building your own route if you ever wish to pursue high-score play:
Since
stranno
broke their own rule and posted multiple shmups of all time, I'll post a few more of my favs:
Galaga '88
Hands down the best pre-shmup from the Golden Era of arcades. Maintains the simplicity of the original Galaxian/Galaga but adds in some frills that keep things enjoyable.
Hellfire
It's not Toaplan's best, but it's one of the first shmups I fell in love with ~30 years ago.
Sexy Parodius
I love Konami's Gradius-likes. The Gradius series itself is amazing and I'm also very fond of the offshoots like Salamander and Parodius. Sexy Parodius isn't good because it has T&A. Sexy Parodius is good because it's an excellent shmup, even edging out Gradius V in my opinion.
ESPgaluda
(includes two playthroughs; the second begins at 31 minutes)
Perhaps
The Perfect Shmup when it comes to casual friendliness matched with brutal high-level play. ESPgaluda grants the player a pool of green gems to power their "kekusei", which allows you to slow down incoming bullets at any time. Kill enemies in non-kekusei mode to gain more green gems to use kekusei more often. This makes complex patterns far more manageable as long as you are stingy with your kekusei usage.
Or, if you're playing for score, abuse kekusei and push the mechanics to their limits for massive points. You can see how the player intentionally lets the screen fill with bullets with the purpose of cancelling them for gold bonus chips.
Twinkle Star Sprites
Unquestionably one of the best games ever to grace arcades. So simple that a filthy casual can understand it. Endless competitive fun.