MegaMari is a Japanese PC game that is essentially a cross between Mega Man 2 and Gradius with a few features from other Mega Man games thrown in. I don’t own the game, but from what I read online, it is evidently part of a series.
Thanks to Lake Hikari Asakura for first bringing this to my attention.
I haven’t played the game, but I grabbed a few interesting screen shots from the demo sequence off the official website.

Jump and shoot the MariBuster!
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Appearing and disappearing blocks over the spikes of doom.
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Gradius part one.
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Gradius part two.
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