99 - Dodonpachi (Arcade)
Balancing precariously on the point where bullet hell shmups took over more traditional ones in the arcades, this is still my favourite from the Cave stable. From a gameplay point of view it eases you in quite gently, gradually throwing more and more at you. Unlike the ultra-niche domain the genre has become these days, Dodonpachi makes you believe you can actually crack it without spending every waking moment of your existence memorizing bullet patterns and scoring systems.
The icing on the cake is that it's gloriously noisy and it has a kind of gritty low-tech look to it that perfectly fits the no-nonsense destruction.