Man, I don't even know how to judge this game. Because it's an obligate multiplayer game that apparently takes place over several weeks, I don't feel I got the full experience. In fact, I still don't understand all of the game's mechanics. I'll start by describing what happened in my time playing.
I first tried out the game on the web client. It took a very long time to load in. In fact, I got up to grab a snack while it was loading and came back to see I had been killed. After a few more minutes of playing, I switched to the desktop client since the web client felt sluggish and unresponsive.
I didn't see any other players around, so I just played the game as I would Minecraft. I crafted my stone tools, found a cave, and explored it, finding some iron to craft some tools and armor. I was basically just playing off-brand Minecraft. I was still unsure of what exactly my goal was. I was told by the game page that I was supposed to be fighting aliens, but nobody else seemed to be on the server. I really didn't know what the spreading corruption was for either.
Then you and a couple other people joined the server. It was only then that I found out I was an alien, since you told me to press C to examine my player model. (It was like a bad M. Night Shyamalan movie; *I* was the alien the whole time!) I wandered around corrupting forest land. Then I stumbled upon a human player, killed him pretty easily, and then...well I didn't know what to do after that. All the humans were alien-ified so there was nothing left to do.
This game is a hat on a hat on a hat on a hat. It's built into an existing game, it's multiplayer, it takes more than a single sitting to fully experience, and it has very confusing and ill-explained mechanics. And if one hasn't played Minecraft before (I have, but not everyone has), then it becomes even *more* confusing!
Here is what advice I can give (keeping in mind that I don't know what is possible with Minetest): - Remove anything that isn't absolutely critical to your game. For example, one of the crafting recipes was for a screwdriver for rotating decorative blocks. This is not necessary to have in your game about fighting aliens. - Make it very clear whether or not you are an alien. It should be obvious just from looking at your first-person view which side you're on. - Create some sort of singleplayer mode that lets the player get to grips with the mechanics. Multiplayer pvp can be a stressful environment, especially when you have no room for failure if you want to remain a human. - Create some sort of tutorial or quest system so the player can understand how to play. At one point, the game told me through console that I was full and I should build a new heart to spend my biomass. But I could never figure out how to actually do that. (And a side note, the heart's menu text was cut off. All of the options said "00 biomass", so I couldn't see what anything cost.) - Create an ultimate goal for the players on each team to work toward. When we harvested all the humans, I would expect there to be a celebratory "Aliens win!" followed by a map reset for the next match. But nothing happened. I just ran around exploring the terrain until I got bored and logged off. - Don't make a multiplayer game that relies on there being multiple people on the server at a time. It makes it very hard to judge your game. I didn't find out about this game until after your gameday had passed.
I know, it's a three-day game jam so adding the stuff I mentioned would be a lot of work, but that's why you need to scope well. It's an admirable effort, but I think what you tried to make was just too ambitous and ill-fitting of a game jam like Ludum Dare.