1) About the game being ugly - perhaps simple would be better. The more crude the monsters the more you can have at one time ... it is better this way. The main thing is how the monsters feel and are experienced which is great I like them simple and ugly.
2) I understand the problem with the hearts spawning. It feels like you walk for ages and find nothing but if you wait until nightfall they start spawning.
3) The stone bullets work for now and your plan for making use of unique ammo is cool (bullet factories using multiple ingredients .. chemistry).
4) The difficulty is pretty low at the moments (except for the abomination ... that is strong). THe mobs really just become XP farms. It would be nice if the monsters got progressivelt stronger as you increased your base/ production. This would force you to improve your defenses with the better ammunition idea.
5) Is there plans to add creative mode? I would like to mess around with stuff but I am limited by resources and day night cycles. Any plans to add a mode where yo ucan build anything for free.
6) If you look at Terraria and Don't Starve - they did not have endless maps but people still love playing them multiplayer. And since you can always travel to another world and keep your character then why bother with the endless map. Once you get more biomes and more layers to the map and perhaps some dungeons, places of interest, the map will feel unique. A unique and interesting world would be better than a vast endless world where nothing means anything. Like dwarf fortress, the map was not endless but it felt like there were many possibilities.
And you can still set the spawn to make huge maps with many square kilometers of land but it should have an end. This can make for maps that have a unique shape perhaps ... islands or central mountains or double continents. I have made multiple worlds already but none of them meant anything or stood out particularly much - if you walk long enough your going to find a place that has copper, tin, iron, coal in abundance and your are set. If your plans for multiplayer are in the 1,000s then have you considered PvP ? If the map is not endless it would force people to compete ... it is a crazy idea. Have you ever played 7DaystoDie? Its world is not infinite but it is pretty damn huge and you will probably reach a stopping point (climbed every mountain, killed every challenge, built every item, found every treasure) before you explore everything. Then you start a new world and see what new challanges that world has to offer.
These worlds are not completely random, they are procedurally generated so even in a finite world you can guarantee that EVERY biome will spawn and it will have a minimum amount of dungeons for example.
Lets think about the stone turrets for example ... you have a very large selection of turrets and lasers but in the end you and I both just used stone because it worked. More options does not always lead to meaningful gameplay. Your turret list is basically infinite in the idea that I will never make my way through it. I will never build every laser because it is pointless. Exploring an infinite world could become pointless. But if the world is smaller but more dynamic, unique, and is filled with emergent gameplay opportunities then it could be worth it.
For example, thinking completely crazy in the future .... imagine creating a world with randomly allocated slider bars for mountains, lava, swamps, cities, caves, trees, deserts, islands - like a full complement of world generating madness. But you are unaware of these at world start. (ofcourse you can manually mess with these to make like water world if you felt like it). You start your aventure ... you find yourself spawning between a village biome of goblins (?) and a lava biome of demons (?). You find a cliff between these two biomes to make your base ... it is defensible and you can kill off the goblins and demons that come trying to kill you every night. You get ores, your moving up, you decide to dig down into the mountain and find your base is directly over a undead biome underground, vampires are now trying to kill you. You have to build different towes to kill each threat, you have to make a decision about which group to kill first perhaps. Maybe you can tech up to terraforming and completely wipe out one biome (freeze the lava pools maybe) ... or negotiate with one of them. The game world has to challenge you to survive against it and succeed. I have made one laser in your game and it served no purpose but it looked cool and was satisfying but I did not need to build it because the world was not forcing me to need a laser. In an infinite world - you can always overcome any obstacle by walking in another direction (ugh .. I built my base on top of vampires ... I will simply relocate) . In a finite world you are stuck and must fight. If you want to build a large base you must fight to carve that base out of the environment - threats and all.
I recently made a base in your game in a terrible location with low resources and decided to try making coal from trees. This led to around an hour or so of me just learning how the whole process worked, fine tuning the production chains. I had ot experiment with bio compressers, the coal making device . I had like eight compressors going into one coal making thing. It was fun and I still have not gotten it down to the most streamlined model of trees ----> leaves/sticks ---> lumber ----> coal. THat is what I like about Evolvdustry is organizing resources, production, base building, defendin my forest because I also had to discover that monster will eat your trees. You cannot make bullets out of forest biome so I had to snake a conveyor around to supply turrets. This whole process about making coal from trees was fun but UTTERLY POINTLESS :) becuase I simply could have kept walking until i found a giant coal field next to an iron patch. The only reason I did it was becuase I wanted to see what it was like to build a base in a terrible location. In an inifnite world you would always be able to build a base in optimal surroundings - in a finite world you have to figure it out and make it work - that is where the fun is. And you can always head off to a new world at any time for variety.
But your game is awesome, I could play this for thousands of hours and see limitless potential. Mindustry, Terraria, Fortresscraft, Minecraft, 7DaystoDie, Don't Starve all rolled up into one game with a simple 2D top down aesthetic . Imagine the kind of mods people will make for this game? lol