Hi there.
I bought your game Super Space Meltdown on Steam, but after downloading it, it just doesn't start.
I've noticed that this game doesn't work for all steam players and no one have found a solution.
I use Windows 10 64 bit.
Not relevant to itch.io app
I've sent a PM to https://twitter.com/itchio. I don't know if there is a public e mail.
No I meant send a message to the developer of the game you're wanting to play, not to the itch.io admin team. If they've uploaded their game to itch.io you'll probably find their contact details (Twitter, email, Facebook.etc) on their itch.io profile page or the game page.
Itch.io simply acts as a marketplace and doesn't have any involvement in the development of the game.
Steam really isn't as good as what many people would lead you to believe - I personally have a few choice words to say about the Steam "service" (although my reasons for disliking Steam are probably different to yours.)
I do have a Steam acc, but I've not logged into it since mid-2012 after I saw how much of a wreck it really is.