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Trigger, by indie developer increpare is a side scrolling shooter with simple graphics, but targeted to addicted gamers looking for a challenge on the genre.
The following video is a speedrun, so spoilers etc… (if you plan to play it through, watch some bits of it just to know what you’ll face):

The gameplay is pretty simple too. Your ship has a weapon that allows you to lock on to multiple targets, and then shoot them directly.
Fun for hardcore side scrolling gamers, lots of frustration for normal gamers… 😛
The game is free, you can get it at Increpare’s official Trigger website.

Source: IndieGames