Sorry about that, it's in no way dangerous of course, but not sure of the best work around. I know when I get those messages there's usually an option to "open anyway"
edit: just tested it, it says it's an "unrecognized app", I clicked on "more info" then " run anyway" at the bottom. It's up to you of course, but as I said it's not dangerous and I've opened countless indie games that gave the same message