lgogdownloader --repair --game game_name_here --no-extras
This will also repair the file if it is corrupted

How do you do that (on Windows)?

Not sure what polynomial length was used, but a guy did a performance analysis on Stackoverflow and determined that there wasn't much of a performance difference between MD5 and CRC.

It's true that MD5 have been broken and CRC was never meant to foil an attack to begin with, but let's face it, we don't do integrity check on our collection in case some weirdo decides to silently corrupt our GOG files in an undetectable manner. It's hard disk malfunctions we are really worried about.

Well, you can always use the tool I programmed if you find the others tedious.

In the utility prompt, you run "verify -m -s *" and then go do something else

Almost sounds like my tool, except that mine only reports problems (and lets you decide how you want to address them).

I'm now entertaining the notion of it letting you repair bad game folders using a redundant copy if you have one.

Keeping the database update with future updates is actually not that hard, because GOG now warns you when there is an update.

It's the updates they didn't warn me about in the past that are giving me issues.

My final post in this thread explains why updating the database with my entire collection is slow: http://www.gog.com/forum/general/library_size

And yes, my GOG collection is constantly growing.

However, JMich has a lot of games too.

I'm looking forward to do that merge with what he has once he produces a database which he is relatively confident won't have surplus files. To be fair, there were bugs with the exclusion list in the previous versions (as I don't need to use it myself) so he had to wait for me to fix them.

Yeah, I'll do the fork.

Right Click->Properties->Digital Signatures. Select the GOG Limited one (should be the only one) and click Details. If it says "Digital Signature is OK", the file passes the integrity check.

Thanks!

I'll have one uploaded during the weekend, currently trying to see if some items are parsed twice or not, so I'll say (again) screw this and do a clean parsing.

@Connie
Here is a file with a bunch of xmls, containing the base64 md5 and sha1 hashes of the games I have. Before asking why they are stored that way, it's because I was using fciv to get the hashes, and it stores them encoded. I think it should be up to date, if you wish for a specific hash, do ask.

There were past problems with game recognition due to GOG changing base windows installer names between versions.

Now that the utility uses manuals, patches, soundtracks and Mac installers to recognize games as well, this problem is greatly mitigated.

Either way, there is a "unique" constrain on game folders and game titles in the database so the utility will crash before generating a redundant entry (a preferable scenario imo).

On the link in the previous post, check the log.txt for the (start) of my last attempt to update, after grabbing some of the promo games. Unfortunately, the computer decided to reboot in the middle of the night, thus I couldn't see the rest of the log. Thus why I say I'll do a complete re-scan.

Dat and md5 files (from verified sources) now updated.
Check my "#Missing and to Verify (20130316).txt" file to see what I still need help getting CRC, hash and size values for.

My GOG.com Project - http://sdrv.ms/UXVDke

just wanted to add my thanks for this; i remember during my first few purchases wondering if there was a MD5 Hash knocking about

Good stuff!

...and thanks for helping me (and others) with this.

EDIT:
After a recheck, I think someone's version of Mutant Mudds is corrupt according to a sql file. I have file size: 125072664 bytes

Update:
Added 7 games to the files listed in the original post:
- Blade of Darkness
- Deponia 2: Chaos on Deponia
- King’s Bounty: Crossworlds GOTY
- Lucius
- Miasmata
- Primordia
- Waking Mars

Updated information about 37 older games (files added, removed or modified):
- Back to the Future: The Game
- Blitzkrieg 2 Anthology
- Blitzkrieg Anthology
- Book of Unwritten Tales, The
- Capitalism 2
- Darklands
- Darwinia
- DEFCON
- Forgotten Realms: Demon Stone
- FTL: Faster Than Light
- Guilty Gear X2 #Reload
- Icewind Dale 2 Complete
- IL-2 Sturmovik™: 1946
- Incredipede
- Inquisitor
- Legend of Grimrock
- Lionheart: Legacy of the Crusader
- Lords of the Realm: Royal Edition
- Mutant Mudds
- Perimeter
- Pid
- Pinball Gold Pack
- Redneck Rampage Collection
- Retro City Rampage
- RollerCoaster Tycoon: Deluxe
- Sid Meier's Alpha Centauri™
- SimCity 2000™ Special Edition
- Soldiers: Heroes of World War II
- Tomb Raider 1+2+3
- Total Annihilation: Commander Pack
- Ultima™ 1+2+3
- Ultima™ 4+5+6
- Ultima™ 7 The Complete Edition
- Ultima® Underworld 1+2
- Wing Commander™ 1+2
- Zork Anthology, The
- Zork: Grand Inquisitor

Thank you! :)

This will keep me busy checking for a while.

Hmm... it looks like there might of have been a silent update of Medal of Honor Warchest. Here's the MD5sum from the setup files I downloaded yesterday. I was able to successfully install from them and played the first level.

3030b7213476b14fe52719083792d6ff setup_medal_of_honor_2.0.0.21-1.bin
a5538ad0837208b065cd8b10229ba717 setup_medal_of_honor_2.0.0.21-2.bin
2f5dd640b3994d67fc71995b743cb22c setup_medal_of_honor_2.0.0.21.exe