So, I briefly looked through your game. You very specifically did not ask for folks to do this, so I hope it's okay to share my thoughts here. Apologies if this is unwanted. I did not do a close read at all but I did try and make a determination about my own opinion regarding the "OSRishness" of your heartbreaker.(SNIP original post...)
Firstly, whenever I look through an OSR game, I have a specific goal. Is there a rule I can steal and stitch into my own set of houserules, making them a more perfect Frankenstein's game? And I found that rule. Almost immediately.
I will be using your "Gambit" rules. Maybe not in every game I run, but often. I don't know if it's an original rule of your own creation or just something you took from somewhere else. Either way, it's a great rule. Very possibly the best rule for critical success and failure that I've seen. Very good. Made the reading worthwhile all on its own. Thank you for that.
So, by that determination your game definitely meets my DIY/OSR needs.
On the whole though, I think you're right to not call this an OSR game. Too many small changes. The way you calculate hit points is a big deviation. And your attributes. Not only do you drop the 3-18 spread (and rolled attributes entirely!), but you eliminate one attribute entirely and split another into two. No classes. Nothing even vaguely resembling Vancian spellcasting. All of this is very fine, but all together it pushes things out of the admittedly vague OSR box and into a more independent space.
But this has nothing to do with the XP system, which is great. And also includes two variants of gp-as-xp as optional rules. Right in the text. So it's weird how people focus on different things as their determining factors. For your friend, it's counting xp based on something concrete. For me, it's the original ability scores, which may be renamed or retooled but should not be eliminated. Heh.
I can absolutely see how it would feel OSR to you, however. You know where you started and probably made all of these changes incrementally. The game never lost that primordial feel to you. But speaking as somebody who looks only at the endpoint, I think you're looking at an original game more than any kind of retro D&D. There's very limited compatibility without significant conversion, which to me is the most important factor.
I didn't have time to dig into the specifics of your magic system but I look forward to doing so. I am certain that I'll find more rules and ideas to steal.
The game was much better than I expected with a $1 pricetag. You could probably go PWYW and make a bit more money.
In closing, I'll leave you with something I absolutely loved. In the description for Charisma you include this sentence: "Those who want to become legends will invest here."