Half-Life: Xen's Horror is a Half-Life mod where you play as a guy named Ayden Farrell who discovers the lost facility named Orange Facility. A little more bio, Ayden discoverers some devastating and horrible experiments which gone wrong and with the collapse of the alien world Xen are making their way to the human world.
It's better to create one high-quality mod than 100 low-quality ones. This is really bad and looks more like spam. I'm serious; if I create a mod with a level generator (RoadMap), for example, it will be much better. Well done for learning, but you don’t have to constantly post your super mods.
Note: Played Demo V2.1.1
As a mod developer myself, it would be tricky to write a review from the player's perspective for me, so keep that in mind.
The demo is short and simple, but I won't include it in the overall score.
The gameplay consists of pushing the buttons, opening doors and shooting zombies, which is overall repetitive and needs rethinking.
The environment, albeit not empty (I've noticed that you put a decent amount of work in details), could be much less blockier as the cubes certainly destroy the overall mood. There are many places where brushwork and texturework needs to be fixed, e.g. couple of ant doors (even if they're closed), surface of water flying behind windows (that's kind of engine limitation but you can just make window to be above the surface) or reversed texture medical charger.
My main advice stands still: keep learning, look what other people did with HL1, and "steal" their tricks. After all, before I created maps for FI, I was too involved in some bizarrely simple brushworks :)