Han's alternative EXE called Launch was recently updated! Most people use Kentie's Deus Exe, but I'd really recommend people switch to Launch. It's still being developed, requires no dependencies, and is in my experience at least more stable.

I apparently forgot / didn't know about title overflow, sorry still new to GOG!

www.patreon.com/posts/launch-20190603-27335560

Welcome to the forums, not so new customer!

I'm using this launcher aswell because the game doesnt want to boot.
I remember playing it a long time ago without any isssue but now it's just impossible.
Kentie's launcher doesnt work for either, I tried several versions of the game through GOG galaxy launcher.

I noticed 2 things
- the first launch of deus ex is working, but right at the second, the game just hangs out in task, 100% cpu and nothing is booting.
- renaming the deusex.exe works and the game boots but just once then the second time it's not working anymore.
Maybe it's a regedit issue? Any gog team are working on this or??

The problem using another launcher is that galaxy features are not working properly, or working at all.

Other big issue using alternate launcher :
Using the other launcher helps me play the game BUT there is another technical issue, and a sizable one : when i quit the game, my windows 7 is what appears to be in 16 bits colors.... Restarting the OS fixes that, unloging from my session and going back to it reset the graphical setting for the OS too. So if any person notice something different right after exiting the game, now you now how to deal with it! :p

Have you tried it outside of Galaxy?