This post might help.

So the classic installers won't have the integrity check anymore? Is there any chance we'll see the MD5 checksums on the game shelf in the future?

I ask my friends find old & new GOG versions and send me screenshots of Option page.

Examples:

Firewatch, Obduction
And new title - Ash of Gods

All examples - multiparted installers, and can`t be full verified by digital signature.

See comparison in attachment

I don't have the games you mentioned so I can't check them. It's strange though that Risen which got new installers just two or three days ago still has them while these games don't.

GOG's installers are maintained by different people.
And, GOG do not have a detailed guideline for how to compile their installers.
(Maybe they have the guideline, but too many GOG installers are not follow the guideline.)

I can only assume, that GOG has different team of programmers.
One use old version of installer builder, with integrity check.
Another use different without it.

My friends said that new installers besides has internal install of VisualC`s ( which created no other windows during installation - all installed in main process). And one of new installer (Sudden strike 4) has internal select of game language.

Just bumping this topic, as I had messaged GOG about this and they're asking for the titles of games that don't have the integrity check option. This is for games that are separated into more than one download and feature .bin files .

It would be mighty helpful, if some of the gog members could kindly check which titles are missing the integrity check and mention it in this thread. That way, one could easily forward the names and have gog take a look at it.

Just posting the message here I got from support.. Also, if there are any other titles that are missing the option for integrity check,kindly mention it here so that it would be easy for gog support when they check this thread or you could message one of the blues.