@Jarek I didn't know about the multiplyer for graphics off, that is a good idea.
I always think unlockables and things to work towards a great addition, particularly to arcade style games, since it means when you play your not just getting score, but working towards some achievements or pirzes so I'd be a huge fan of that.
I would not recommend Steam since the steam program itself is not friendly to screen readers and requires lots of mucking around with ocr addons to work, valve have been told about this but don't give a dam about accessibility.
of the services you mention, probably Itch.io would be reasonable to use, but any service where the game can be easily just downloaded and run with the minimum of messing with inconvenient websites or interfaces that might not be good for screen readers, heck while you might consider places like humble bundle for purposes of appealing to a wider audience the absolutely best and most friendly alternative is still just to sell the game via your own site and use paypal for payment.
With our dreaming and singing, Ceaseless and sorrowless we! The glory about us clinging Of the glorious futures we see,
Our souls with high music ringing; O men! It must ever be
That we dwell in our dreaming and singing, A little apart from ye. (Arthur O'Shaughnessy 1873.)