I can really see the shelldiver influences in the upgrade tree.
Positives:
1. I really like the way the timer leads into each run. It's very visually pleasing.
2. I like the 'random encounter' stuff after missions.
3. I think the logo looks great, has a nice visual style
Improvement areas:
1. The upgrade tooltips should disappear when you're not mousing over them. Currently the last moused-over stays up, which sometimes blocks other UI elements (e.g., "Dungeon").
2. Related to the above, I have multiple times bought an upgrade I didn't want because I used LMB to pan up the screen instead of RMB, and instead of panning, it simply bought the currently focused upgrade.
3. The music volume differential between upgrade screen and in-game is stark, If you turn the volume to what makes the upgrade screen music audible, the UI sounds are way too loud, and vice versa
4. As far as I could tell there was no penalty for dying before the end of the run, the presence of this can add some stakes. Currently the only thing that happens is you finish the run early as far as I can tell.
5. The fact that the velocity of the sword swipe projectile does not depend on your direction of movement heavily overincentivises kiting the mobs because your slash travels 2x as deep into a crowd if you're going backwards, and conversely, if you are travelling forwards it doesn't travel far enough forwards for you to not get hit. Not sure if this was intentional or not.
6. It took way too long to realise the class upgrades don't do anything besides opening more upgrades. I spent so long looking for a way to switch classes.
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Closing statement:
I played for about 15 minutes before bouncing off of it primarily due to how ineffectual the attacks felt despite the mobs getting stronger and more plentiful the more upgrades I got. It felt like reverse power creep.
I have no clue how long it takes to make a game, and if this was your 1st or your 50th. 2 weeks sounds like hardly any time at all, so given that I'd say this is a good early effort. I hope you choose to work on and improve it rather than just moving on to the next project, as I think with some balancing tweaks and UI improvements it could be a fun game!