The 3D casino scene is really well put together. First person in front of a machine, more machines down the sides, chequered carpet, dark grid ceiling and an empty armchair beside you. It genuinely feels like an empty casino at 4am, slightly depressing, which is exactly the right mood for what this game is about.
The background posters are the joke and they land. One says "CHANCE ZERO." and the other, huge, just says "LOSE!". After I lost, it changed to "LOSE! TRY AGAIN?". That's good satire: the entire environment is telling you the truth and you pull the lever anyway. The machine itself is nicely modelled too, gold top reading BIG $100.000 WIN, the grapes and banana and BAR and 7, the !JACKPOT! 777 panel.
And the giant red arrow pointing at the lever on your first play is a zero cost visual tutorial that works perfectly. The HUD is direct as well, money with a combo multiplier and a spins counter, and using consecutive wins as the multiplier is the right mechanic for this theme.
Where I struggled. Starting with only 3 spins and $0 is harsh, I lost a third of my resources on the first pull and was immediately negative. It also never became clear how I earn spins back or what I actually do with the debt. Your description mentions a deep upgrade tree and I couldn't find how to reach it, which is a shame because the debt-as-tactic idea is the interesting part. And the lever only responded to a click exactly on it.
Great atmosphere, and the poster gag is worth the visit by itself.