I also have been trying a lot of demos lately, here are my thoughts.
Voin - First person extraction action rpg with some pretty views. Protagonist looks like something straight from the metal album and slashing zombies feels nice but the gameplay loop itself didn't grab me. Dev likes making you walk a lot for some reason.
Mohrta - very stylish GZDoom based retro FPS. Very interesting locales to look at(HUB area especially) but gameplay is honestly lacking and in some places feel tedious. Shotgun primary feels weak, healing doll is very cute.
Tribe Nation - FTL but you're playing as celts trying to escape romans and you command armies on hex grids. Can pillage softly, normally or hard. Like visual style.
Second Sun - mindless but surprisingly fun. Demo left me wanting for more.
HARK THE GHOUL - definitely one of the steam next highlights for me, even made a
thread for it. Dark Messiah/King's field-like with a fun to explore world and cool unique items.
Commander Quest - deckbuilder/auto battle strategy game where you play as reincarnated historical figures in a fantasy world. Summon squads with your cards and watch them clash with the enemy squads on different lanes. You can summon towers, giant eagles that don't require a designated spot for summoning, place fire, call rogue/assassin squads in the rear of enemy and stuff.
Kinda like the presentation and there is quite a bit of content in the demo. I am yet to beat the final boss fight.
Metal Bringer - frantic action roguelike where you create and send your remote controlled android into the outside world to battle large hordes of enemies. Your android in turn can pilot mechs to help with the hordes and against enemy mechs. You can then steal the later limbs to replace your own damaged ones or outright hijack defeated mechs if yours is too worn down.
This whole appropriating enemy parts reminded me of Metal Fatigue. Like the concept and in Metal Bringer the execution is pretty fun as certain parts can radically alter how your mech moves and attacks.
Not sure how to feel about the meta progression where you need to spend money to analyze data disks(improves android stats) and mecha parts(allows you to assemble mech at the start of the run). Analyzing mech parts is very expensive so it's unlikely that you will be able to assemble your own mech before demo timer runs out.
All in all, this one is another highlight for me.
Aether Singularity - a Parasite Eve inspired game about FBI agents fighting demons. Found it kinda hard.
Steam page blurb says that there will be a time limit that will affect your ending. Sucks for me because i like taking my sweet time exploring places.
Demo is really short but there are extra combat challenges you can try.
CONERU -DIMENSION GIRL-
"A 2D Platformer "Date" Action" where you play as android powered by a girl from another dimension. You're on a quest to save the city from alien group known as "Hateful Fruit Company" and you can throw moon at people. The most genuinely stupid fun game that i have tried amongst these demos.
SNØ: Ultimate Freeriding - comfy little skiing game, demo is turbo short.
Anode Heart: Layer Null - a pokemon-like game where you duel people in a card game. Like the concept but i didn't like the card game itself. Might be a skill issue but i feel like it's way too easy for a single bad hand to decide the match due to the fact that both players have only 3 HP.
Vivid World - auto battler roguelike where you assemble a squad of viking/pirates/whatnots in the pseudo afterlife and collect gems. Don't have much to say about it other than that artsyle is cute.
Secret Agent Wizard Boy and the International Crime Syndicate
It's a hitman-like game where you must figure out how to progress and complete objectives as an undercover agent in a NotHogwarts.
There are physics and a bunch of secrets that you can stumble upon in the demo level.
Junky but really fun.