I looked through a bunch of the recent Next Fest demos, and here are the ones I found worth checking out:

Platformers:

Physics are kinda wonky sometimes (even getting me killed once), but the game shows promise.

Solid platformer. Doesn’t do much unique, but does it well. Almost flawless.

Killing enemies to charge the higher-jump is odd, but the teleport-gun has solid implementation.

Another quality title with a well-implemented gimmick. The escape level gets close to being too long without a checkpoint, though.

The wing-boost (midair-jump) takes some getting-used-to, but the demo only has four short levels, so you won’t. Still okay, though.

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SHMUPs:

Decent bullet hell, though the demo’s last boss started to breach unfair territory.

Bullet hell, but almost nothing is unfair (at least on Normal mode), and the demo has 13 two-phase bosses!

Promises different paths for each character, but the demo only has one level (the same for each one). It’s an okay level, though.