First impression:
The graphics seem a little inconsistent, though I love the artwork! Between the title being vector art, menu background being 'water color' style and menu buttons being pixel art, I would say picking one for the overall art direction would be best. I love the water color style, and I could see some really awesome spine animations in that style really nailing the 'casino' / 'motel art' vibe. haha. Just a nitpick, but something worth investing in if you want to expand the game maybe. :)
I love the music and sounds, but same kind of critique. Between the soft 'speakeasy' piano and 8 bit button hovers, I would say picking a style and sticking with it would feel more cohesive. I like high-definition sound effects personally, and the piano music so I think adding things like 'glass klinks', 'suitcase drops', and 'page flips' would really match the vibe for different UI sounds. :)
I gotta say, though, the music is incredible for this one! I am in love with it!
I love the intital vibe of the game! I am a sucker for HD lighting on pixel art. haha. Feels 'home-y' and has a cozy feel to it from the rip! The shop is nicely done as well! Very fluid. I think some kind of 'negative feedback' would help, as I kept thinking I was buying items even though I didn't have any money. haha. I also think having the descriptions for each power up reguardless of if I am hovering would be nice, That way I could quickly scan between the items and compare effects instead of needing to hover over them each time.
The mechanics are very solid and consistent. Shot, Dash, Kill or be killed. I really enjoy the simplicity of the design, and a lot of the powerups seem well balanced. I like that you equip them to a roulette wheel. I think a couple of the items could be a bit cheaper, such as "Bet the farm" being 20 coins, but has a pretty bad negative side effect for that price (bosses have much more health than the player, and as such Health is a more vital asset). "Doubling down" is by far the better option as you only lose 1 HP but get a 4X. It can be a bit offset by "Against all odds" but when my HP is low, Id rather have more healing effects like "Ace up your sleeve" than damage effects.
Maybe reducing the price of that item would make it more worth the risk, but otherwise I didn't use it. Same thing with "Double or nothing" being a chance item (I had some simliar issues with some items in my game as well), Why pay so much for the possible downside? I think lowering those two in cost would make them more valuable in the short game, as long term they feel more like a net negative and thus I wouldn't ever use them. (but again, this is just my opinion so take it with a grain of salt. haha)
Overall, a really fun entry! I wish it was longer!! Would love more items and bosses! Definately would like to see it expanded! Great work!