Hey, I played on Windows.

So, overall, very fun and satisfying TD game!  I like TD, but don't play too often, so don't know the current state of the genre.  I think the "torture" mining feature is a nice added strategic element, though it seemed that I would max out at like 4 souls, so not sure if I was doing something wrong?  Was there something else I could do to increase my capacity (I mostly built the two different types of crucifixes, but got up to like 10 of them).  The differences in towers is interesting, but by the end I mainly focused on the snake for armor piercing, and the long range one that is 60.  I don't know if I missed it, but I didn't realize I could upgrade towers until the last level!  Didn't seem too necessary though, but adds another interesting strategic element.  The art works, and the different enemy types are good.  One note on the first level, you should make the enemy path more clear.  I figured it out quickly, but on my first look it was confusing.   As you're working to balance and design the enemies and towers, you might want to check out this video by Steve Lee about orthogonal design: Every game designer should understand Orthogonal Design .  Basically it's about how when you're designing things, you can simplify the design by making things categorically different, rather than just increasing/decreasing stats.  Like the snake tower has a clear purpose that is different from all the others (armor piercing).  But that long range tower is just a stronger version of the first tower, so the first tower stops being useful other than being a bargain.   You've kind of already have some of that, though I never saw much benefit in the fire or area attacks.  You might be able to think of creative ways to make that more clear.  There's some places where you can polish, like some of the clicking interactions aren't smooth, and the UI can use some work.  Also the pixel text is kind of hard to read.  But overall you have a really strong core, and I didn't encounter any bugs.  Great work!

I played on Linux using Wine.

The main menu has mouse hover effects, but many other interactable elements do not, including the Options. In the options the Sound option does not provide any feedback on if it does anything. It would be good to add an indicator of the sound level/mute there, as well as playing a sound to indicate the volume.

The biggest thing I noticed was once I started the first level. I could click on the towers, tower type tabs, and the sound button. The sound button toggled when clicked, though there were no sounds to see if it did anything. Clicking on a tower selected it, but it appeared at the top left and clicking most places made it deselect. Pressing the keyboard keys indicated or clicking in most places, did nothing. Even trying to press escape to pull up a menu did nothing. Eventually I started pressing everything and found pressing space would advance the dialog. With the dialog blocking most actions, it should start with indicating how to advance it. I would also add the ability to click on the dialog to advance it, as well as allowing escape to work even when it is shown.

I like pixel art. Overall the art is decent, though could use a bit more polish, including animations. The font is not always the most readable, and might be an issue for some users, though I know that being low res there is a limit to what you can do. The UI could use some work. As mentioned above, mouse hover indicators being added to other interactable elements would help. The tool tips for the towers could use a bit of refining to make the info easier to read at a glance. I'm talking about organizing the data a bit so the details are better spaced/positioned. As an example of something that could be improved, the first tower has the word "range" on one line, while the value of the range is on the next. It would be better if these were on the same line. Cost has no space between the word and the value, but the others do. I'd also give a bit more space between the cost and the text "dmg", making it more like 2 columns. From the look of it I think that whole section with the stats is one big text field, so I know formatting that can be a pain sometimes. You may want to separate it out into multiple fields, or perhaps do some padding of the values before combining them to get the right positioning. It would also be good to update the text with more consistent formatting, such as capitalization. There were a number of typos/spelling/grammar mistakes in the text throughout.

I like playing tower defense games, and this one was pretty good for the early state it is in. Once I figured out the basics I was able to play through all the levels, with only a few where I took any damage on the first try. It would be nice to have a bit more detail on some mechanics, such as the speedup offered by the tower saying it improves nearby towers. What is the range? How much of a boost does it offer? Does it stack? The dungeon buildings could use with a bit more clarity of the use of those with 0 capacity and profit. It would also be nice if when you started a level you had to push a button to start the first wave so you have time to get your towers out, and to read up on any new ones. If not offering that, then hot keys for selecting towers would be nice so you don't need to move the mouse back and forth so much if placing towers near each other, especially at the right side of the screen. 

Overall, this is a good start. The TD mechanics feel good and the difficulty ramps up reasonably.

I pressed H for the tutorial on level three and got this error. Seems like an index error, hope this helps!

# FATAL ERROR in; action number 1; of Draw Event; for object oMain:

Push :: Execution Error - Variable Index [0,8] out of range [1,8] - -1.tut_txt(100196,8)

at gml_Script_tutorial_execut #

stack frame is

gml_Script_tutorial_execut (line -1)

gml_Object_oMain_Draw_0

The game is a great concept. I think the difficulty scales a bit steep, but otherwise, really really cool start. I think maybe a good way to assist in this is to at least start with the $15 torture rack. It makes it tough to get towers in strategic places when I have to save some money to earn money (which is a great idea btw, just tough to start levels). You could even Extend that idea into difficulty. Easy mode you start with 3, hard mode you start with 0. 

The only other real issue I had was inputs being clear. Evengy mentioned some of the issues, but I think that since a tower defense game is mostly mouse controls, I think having at least left click being an action button, and maybe  a button in some places should help with that issue.

I also didn't know that there were any upgrades until reading  evengy's message. Maybe a more in depth tutorial for each mechanic might be helpful for this.

Otherwise, and I cannot stress this enough, this is a really really great start. The art is so great, and the mechanics are so smart. It's hard to find good tower defense games, and this is a great tower defense game.

This game has so much potential content!

I absolutely love the retro vibes of it. It gave me nostalgia chills. 

I didn't see any bugs. 

Visuals are complementing the gameplay. I really love how full on retro this game is!

Some notes:

• In the beginning was not very clear what to do (space to continue the tutorial) But I do appreciate you put the tutorial. I am not sure if that was mentioned in the tutorial - left click on building to see its range and to upgrade/destroy. Also I would place the "how to make profit" closer to the beginning of the tutorial. 
• I couldn't find out how to use the upgrades and how to collect the points in the beginning, because I started to skip tutorial after mentioning the specifics of td games.
• When you destroy the building doesn't give back anything (feels like it should give at least half price back, otherwise I would rather keep the building)
• Another area I would improve is the information about the buildings - to make it available even for unavailable buildings just to have an idea what comes next. 
• One more thing - I think speed up the wave would be handy. 
• Also, credits menu doesn't have "back" button, only ESC works, I would keep the menu consistent with either option available. And I am not sure if the "sound" menu is implemented but it didn't open for me.

Awesome game! thank you for submitting :) I really hope to see it developed further...