Impulse and GamersGate work similar to GoG afaik. You can install and run the games independently to where they were purchased. All it will take is to login with your info on the GamersGate site or the Impulse service and download the games you own in that account. After install they’re independent of the services, you won’t need to run the Impulse software to run the games, and you won’t need further GamersGate logins.
Of course, if a game has its own login systems like say, Modern Warfare 2, Mass Effect 2, or whatever else, and they somehow authorise your specific copy to such an account, meaning you can only create one valid account per copy, you will have the same issue. But you’ll have said issue even if you bought such a game on disc. So, it’s really not a DD issue, it’s an issue with how companies handle cd keys, accounts, etc. Imo it’s clear they’re mostly trying to harm the second hand market rather than piracy or anything else.
Again though, I don’t care about achievements, I care about the game experience. If something is fun to do, I’ll do it even if I don’t earn an achievement. If it’s not fun, then I won’t do it even if there are achievements to be earned. It’s a non issue to me, other issues like the inability to lend games depending on the strictness of such systems are far more important, but again that’s applied to disc releases as well as DD since they’re becoming one and the same and since games use more and more online features that require account creation to offer experiences you can’t have without such systems.
Sometimes such strictness is necessary because it would be easy to otherwise abuse and share the games among many people who can all play at the same time, meaning it’s essentially piracy, but of course that doesn’t mean consumers should be happy with it either. Perhaps games could come with some kind of USB based authorization key (when they come in a box, perhaps some kind of authorization application can be used for DD) which means that this can only be used by 1 person at a time therefor you can lend it out as many times as you want, and you’ll be unable to play it at the time just like if you lent out a disc. I suppose it would still be easy to abuse online however, it’s one thing to share among 10 friends locally and another when you can pass any games you no longer play to 1000s of strangers on the internet, even if it’s only one at a time. Sites and forums dedicated to such sharing would probably pop up overnight, and the issue would be as widespread as piracy, especially for single player titles. It’s a very tricky issue for sure, this ease of use and data sharing with the internet comes at a price, and all possibly solutions will somehow hinder the ease of use for the consumer. USB dongles will be cumbersome to keep and keep switching, online logins will require internet connections even for single player games, etc. There’s really no easy way out. Even just stopping DD altogether and going back to disc only releases would cause backlash.
I agree that they should be able to separate statistics and achievements and such though. I could have for example my Steam login, and then player profiles within. I login to my Steam account, and then I could have a sub-account for me and for my brother with the same games purchased and authorised, but completely different achievements, saves, player data, etc. Since the account login would still be required it wouldn’t make it easier to pirate or anything, and I still couldn’t really lend the games out to others, but at least I could have different statistics per player. I don’t care about achievements but since they can fix that, they should. The same could work for games with their own logins like ME2, I could have a login that authorises the game and the DLC content and what not, and then player profiles within. Otherwise they kinda wanna force you to buy 2 copies even if you play them on the same PC, lol, no thank you.