Pluses of Steam:
* Tried and tested API for online gaming and much more, with services that would cost millions of NOK to develop for each independent developer - available for free
* Immediate, automatic updates and patching
* Integrated game verification and cheat detection
* Direct contact with the world's largest online gamer base, with a lot of social media features, ladders and matchmaking. Even if we created a similar service (which we can't possibly afford to do), you'd have to sign up somewhere to find other people to play, and then every game would need its own service for you to sign up to.
* The easiest game installation process in the known universe
* Once you own the game, a crash is no problem, and switching to a new PC is no problem. Just re-download and re-install. You can have it installed on as many PCs as you want.
* Sharing of savegames between different locales, if you want to (and you will not lose them in a crash, as above).
* Achievements. Yeah, we're suckers for them even if we don't like to admit it
* Lots of free data feedback to developers: what play modes and maps do gamers like, what are they doing in the game, etc, etc. This makes it possible to give players more of what the majority want, not what the loudest people want - and god bless the loudest people
* Direct, immediate feedback on crashes/bugs. If Steam detects several identical crashes, we are told about it immediately, so we can fix it immediately without relying on gamers reporting it accurately and immediately
* Direct sharing of mods and other user-created content with the entire community. You create a mod, you share it and get others to play and comment. Modders may even get paid for mods.
* Thin, memory-effective non-intrusive client
& loads more
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