While on the whole I agree with the consensus here, I will gripe a bit that for Windows games they often bundle patched executables that work on more modern machines, but I often want to run the original (no-CD patched, obviously) game on my older machines. If they offered the older executable as an optional extra, perhaps, I think it'd get full marks from me. Even better if they had an option to download the original CD images for stuff needing CD audio and such. Thankfully, at least right now, the internet archive exists. I like to buy games on GoG or Steam and then download the version that'll actually work for my use case. Worth noting that they use pretty generic Innoinstaller scripts that will run fine on Windows 2000 and later without fuss and Windows 98 with KernelEx, and you can just straight up extract them using innoextract then copy the contents to anything else and it'll usually work without any further fuss. I don't see it modifying registry entries, typically, other than the ones to add it to the Add/Remove Programs list.