They say they do, but you actually need a server to achieve it. They make things over complicated on purpose, because they hate DRM in nature. That's why they cannot be a popular game platform. They don't protect indie developer's game at all.
Their DRM is like nope we don't like DRM and you can verify the email of user if you want.. If you are indie dev and if a small coin is important just ditch itch. :) there's no such a thing called humanity in piracy. Because people who love to steal other people's work say DRM is wrong. lol
"You can use this API call to verify that someone has bought your game on itch.io on your own server. You are responsible for verifying their email address first, otherwise they could attempt to guess an email they don’t own in order to fake ownership."
Users can pay any amount they want to for a game, down to a minimum specified by the uploader. The minimum can be zero. A user can go back and pay more later if they want.
A user can upload immediately upon creating a free account, and submissions are made live immediately. Other than violations of the Acceptable Use policy, any and all content is allowed on itch.io.
Under the hood, itch.io is a generic file repository with no format requirements. This allows binaries for any platform to be hosted. Additional presentation options are provided for web games.
The industry standard is generally quoted as a 70/30 split. Itch.io has an option to change how much money you give to them, from 100% to 0%. The default is 10%, still much lower than the industry standard.
GOG offers the possibility of an advance on your royalties if you're chosen for their platform. If you take the advance, your revenue split is dropped to 60/40 until the advance is repaid. Could be a good way to get your game across the finish line.
GOG may charge more in some regions as publishers request so. But in those cases they give the extra cash back as credits for buying another game.
For example, the lowest price for the game is U$20 in US, but if in your region it costs U$30 they will give you U$10 back as credits for your next purchase.
GOG.com has a policy of always providing feedback in regards to both your game and its place on the platform. Though it does appear that it is often a form letter with little changed for each developer. So while it may be difficult to know exactly why a game was rejected or if GOG even actually looked at it, there will at least be a confirmation of rejection.
Indie games applying to GOG are reportedly rejected using a copy-paste form letter with a few words changed. The personalised feedback promised to users on the indie game submission page is not provided. In at least one case, it has been claimed that GOG did not look at the game's website or download it before rejecting it.
The Greenlight submissions with the most votes are approved in arbitrary batches, generally 50 to 100 per month. No metric is used other than raw quantity of positive votes.
It is too easy for developers to game the Greenlight system and get their horribly broken games on to Steam for sale. this leads to a market that can not be trusted to have only worthwhile working games. It should not be a gamble as to whether or not ones game will work once paid for.
The Concepts section of Greenlight allows incomplete projects to be put on display and receive feedback, including mock-voting as if they were full Greenlight submissions. This can be a valuable tool for refining design, presentation and marketing techniques.
In order to submit games to Greenlight at all, you must first purchase a $100 activation for your Steam account. Note that this does not represent profit for Valve: all proceeds are donated to charity. It is strictly a barrier to entry.
Desura calls their early access program "Alphafunding." Games must show a minimum level of development, and must show active development or risk being removed.
Indie Royale is a joint venture of Desura and IndieGames.com which sells bundles of games on a pay-what-you-want basis (but with a minimum price). Most games sold via Indie Royale bundle are Desura titles.