My favourite #shmup might be Dariusburst: Chronicle Saviours at this point. So much to do, great presentation, fun scoring based around effective beam use.
I've always liked the genre but it was Ikaruga on Dreamcast that really clicked with me, probably because its mechanics are a lot more transparent than many shmups.
Danmaku Unlimited 3 and Crimzon Clover: World Ignition are great entry points. They're solid introductions to bullet hell without being utterly overwhelming.
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