I played a few but these are the ones that immediately jumped out to me. Might make another post after trying out some more demos later.
Crypt Lord: This is a rather low budget, real time, free movement dungeon crawler with a decent amount of effort put into the setting. Sadly the combat could use some work. Attacking is a simple affair where clicking MB1 will perform an attack and MB2 blocks. Mouse positioning does not cause you to swing from different directions (like Ultima Underworld) and blocking is painfully slow which is something I would like to see fixed in the final game.
Skies Above The Great War: A World War 1 flight simulation game with a campaign mode. What is most apparent is a lack of options menu to explain controls to the player. In fact the game does not explain much at all which is a big issue for a game such as this. Most notably, playing the game was something I had to figure out through clicking random icons and pressing keys at random. Eventually I realized clicking on the XBox controller icon which appears upon selecting planes near No Mans Land allows you to start a battle (because Xbox was around during WW1). I cannot recommend this game at the moment due to how barebones it is, just another developer treating the demofest as way to show off their alpha stage game.
A-Space First Assault: A space combat sim which is another barebones proof of concept. The demo has a skirmish mode which allows you to select your wingman and enemy combatants, as of now there are no missions but apparently the game has a level editor so that is a bonus. A-Space controls fine but for some asinine reason the mouse cannot be used to select menus while you in a skirmish. Ask any Freespace or Tie-Fighter veteran and they will tell you how many keybindings a game like this can have. So not being able to quickly navigate what is clearly a mouse centric UI while in combat is annoying. I cannot recommend this game at the moment due but it might be worth checking out in a year or two.
The Legend of Capa Negra: A dark fantasy Diablo clone that, according to its Steam page, has Soulslike elements. To get the cat out of the bag, this game is entirely derivative in all aspects. This game is your standard ARPG through and through with the addition of being able to retrieve your gear upon death which is quite obviously borrowed from the Dark Souls series. Unlike in those games however, Capa Negra provides no lore reason behind this. Dying in Dark Souls has you respawn at a bonfire which makes sense in that games context due to the player character being an undead who is revived upon "dying." After dying in Capa Negra the character respawns at the levels entrance. No frills or originality, HP goes to zero then boom back to the locations beginning. Despite not usually being a fan of games of this genre, I did find this demo fun purely because of combat. Capa Negra allows you to chain attacks, effect enemey movement through magic, and shove enemies which will disrupt their balance. I might also just be interested in an ARPG which includes these elements so time to find some.
Stellar Wanderer: A Freelancer clone, don't see a lot of those, that seems to be in development hell but has recently picked up a publisher. The game is very similar to Freelancer in the fact it has arcadey flight physics, a combination of combat/trade missions, and themed system named after real life places. AI is in need of serious improvement. Half the time they would engage me combat then proceed not to do anything. Another problem is this games overabundance of UI elements. Immediately upon entering space you will not first notice the colorful starting system but instead see fifty target icons all telling you what is in the system. Who needs organic discovery in their games? Just immediately show where everything is so the window lickers won't get lost! Overall I have my apprehensions about this game but still will maintain some interest
Naheulbeuk's Dungeon Master: A comedy focused Dungeon Keeper clone that is not an obnoxious meme filled mess like the Dungeon series. I have mixed feelings on this, the demo never gives you full control since it is just a glorified tutorial. What is present has potential but I will have to wait for the full game to release to make any concrete calls.