Sorry for the late response as I didn't realize that I didn't subscribe to this thread to receive notifications.
4) One of my fears with making the monsters get progressively stronger naturally is that an inexperienced player might get their base that they worked on for hours completely wiped and they just never play the game again out of frustration. A approach I am looking forward to is one that allows the player to gain skill in manufacture, technology and defenses without risking their base is to make the difficulty location based. For instance, if they travel to the Bloodlands , Ice , Desert biomes, etc..., they need to have already unlocked bronze, iron, steel to build stronger kinetic towers or lasers to take on the new monsters that spawn there. Same with the layers of underground, as they go deeper, they need to get better towers, materials, and base building mechanics to survive the monsters down there. This allows the player to progress at their own rate and if they fail, they will only lose that portion of their base (which wouldn't be that large as they just started to expand into that biome). Although, I am thinking of making an endless mode where players can choose to have the game become more and more difficult as time/base progresses.
5) I wasn't going to tell people this but I didn't remove admin commands in the 1.48 version. Currently, you can type "/Set Gamemode Creative", this is cap sensitive and it will make the crafting cost of towers = 0. I'll be adding sliding bars in the world creation selections and in the gameplay panel in the settings.
6) I see what you mean. I can add some settings that allow boundaries to be set and similar which could be very fun and competitive for multiplayer as everyone would be fighting for resources. As for the dungeons, biomes, ect... In an endless world, there can be unlimited amount of dungeons, biomes, and other natural world generations where once a player has explored it, they can find new ones in the world with more unique spawns. Thinking ahead for multiplayer, I was worried that if a griefer found the only dungeon/biome/rift/(other important thing) and they would just ruin it for everyone by destroying it or building their base on it. An unlimited amount would allow for players to have their own dungeon or unique thing in the same world. This is not accounting for the Tryhards that would make it their mission to make the whole map their base and anyone that spawns in could never progress and will be spawn killed by minions or turrets.
As for the stone turrets, currently they are very strong in this version. In future update though, the new biomes and underground will make those towers obsolete for stronger variants basically forcing the player to build the lasers and stronger kinetic towers to progress into the new biomes. But yeah, they are basically endgame currently.
As for custom world generation, I am working on a fully customization, and I mean fully +100 settings to change monster behavior, terrain generation, dungeon spawns, rifts, biomes, replacing certain things with other things, unique commands like spawning bees 1/10 times a tree is cut down or spawn lava, and way more.
For the mods, I am also making a package for Unity (editor I use) that allows anyone to mod the game very easily and it handles all the complex stuff in the background for the modder, but they can override that too. I will also be adding a mod page built into the game that allows other players to share mods and make them public with others with the exception that it has to be approved by me to prevent copyright problems.
I am so glad you liked the game and this is just the alpha version, not polished or anything! Wait until I release the Unity DOTS update which has all the features I've described in recent posts + way more stuff. Thanks again for the discussion as they are very helpful.