Does anyone remember the game Neighbors form Hell (by Jowood)
it was a practical joking game
there was also a sequel neighbors from hell 2

Yes, it was in the GOG catalog until fairly recently when Nordic, the publisher, removed it due to some disagreements on pricing policies.

You're a little late. They were both here on GOG (as a pack), but they were removed about two months ago when GOG introduced regional currencies and they couldn't find an agreement on the price with the publisher Nordic Games (it's most likely that Nordic wanted regional pricing for all their games on GOG).

But you can still find a DRM-free copy of the games on ShinyLoot:

http://www.shinyloot.com/neighbours-from-hell-compilation

Of course I do. I completed both games one month ago. They were pretty funny.

Not at all. it was about the way gOg calculates the prices so they appear differently than in other stores, and Nordic would not be seen to favor one store over another. If gOg just did regional pricing (or kept flat pricing....) like all other stores do them, this would not be a issue.

Strange that they never had a problems with different prices when their games costed $1 more here on GOG than everywhere else ($5.99 instead of $4.99).

I still believe they wanted all their games regional priced (like they are on Steam) and GOG refused. Every other theory doesn't seem logical to me (especially not the one about fairness and them wanting the same price for their games in every digital store).

Then why are they still adding flat-priced games on GamesRepublic and ShinyLoot?

This

because then it was 1 same price for all stores with flat price (gOg, Shiny loot etc) + 1 same price for all stores with regional price (Steam, GG) so there was only 2 price points, and it was equal for all stores that used either system. When gOg introduced the 3'd system to calculate the new prices, Nordic had to either accept that gOg used a completely different system than the 2 previous ones (which the other stores still uses) and accept that 1 store show different prices than any other store, or adjust all other prices to reflect the ones on gOg. Nordic decided that they are too small and do not have the time to constantly adjust prices to match gOg's calculation nor did they want 1 single store to have any different pricing that the others.

tldr; this mess is entirely gOg's own fault for introducing its own regional pricing system calculations, and not using the same system the others stores use

No, it never was like that. The games from Nordic that costed $5.99 always and still cost $4.99 on ShinyLoot (for example Desperados).

http://www.gog.com/forum/general/last_chance_special/post729

http://www.gog.com/forum/general/last_chance_special/post226