what a deep story for a game jam! The idea of "lying" to improve your battle skills was a cool twist. Battle itself works pretty well, although theres some things I think could see some improvement. Imho, the first wave is harder than the second one, and the boss is really okay compared to the other levels (beat him in the first try). Also, you can kind of lure enemies into the spikes which I think does too much damage to them.
Btw, is there more than the two endings? E.g. I did not try beating it without any lies. Or can you survive the mushroom waves that spawn with the full lie bar?