jjen1987: People should accept the fact that, as a rule, there is no such thing as parity between Steam and GOG releases. For starters, we get the offline installers that Steam users do not, and I don't see anybody there complaining that they get less than we do.
offline installers are a store feature, not a game feature that some game developer choose to provide and some didn't.
jjen1987: I'd like to echo what tfishell said a couple of comments above: this is already a niche market compared to Steam, so I am all in for forgetting about achievements if that makes it easier to get DRM-free games. Take Axiom Verge as an example, which was never released here because the developer felt he had to implement achievements for Galaxy and he didn't consider it worth it. Truly a pity.
This would have been an extremely fair point, if the fact that the developer is giving "less" would be taken into account in how they price the game. The issue, as I see it, isn't so much that some games/developer provide achievements on steam releases and not gog releases. It's that they price the game the same on both steam and gog even when the steam games had extra development work invested to add achievement to them, and gog games don't have that feature and didn't have development time invested in it.
Look, personally I very rarely give a ___ about achievements themselves. It happens, for some games that have interesting ones, but it's very rare, and for those few cases I'd be just as happy with in-game ones.
But, it's the general issue, not the specific.
I also generally don't really care about, say, soundtracks, or art books. Sometimes yes, but usually no. Certainly additional soundtrack or art book don't change in any way how the game itself play, make the game any lesser, or modifies in any way the enjoyment from the game itself.
But, if one store sells the game with the soundtrack included in the price, and another sells it for the same price without the soundtrack, it would be a problem.
It's fine to give me less on a certain store than on another, but if you sell less, sell if for less.
Now, would I do something like boycott a publisher/developer if they do that? No, I don't care about it that much. But it certainly would affect how I see them in terms of business practices / ethics, and would certainly affect at what price I'd be willing to buy the game and would consider a "fair" cost for it. Since even though at some point I certainly would think a good game is worth my money, when the publisher actively and explicitly overprices their game on one store over another (selling less for the same cost is overpricing), I will consider it overpriced at that store and will want to pay noticeably less to compensate.
And, well, while for me it's a pricing difference issue, not a boycott level problem, I can certainly understand people who take it harder. If you think a publisher is being unfair on a certain store, simply outright not buying from them on that store is... legitimate.