Dreamcast/Homebrew

The indie & homebrew game list
As hackers figured how to boot the Dreamcast from regular CDs without any hardware modding, it became, by all practical means, the most open console ever. That is, until intentionally open consoles came out, such as the Linux-based Caanoo and many Android-based portables, but I digress. Retaining a devoted fanbase even after it was commercially discontinued, it was the platform of choice for many independent developers. Thus it received several original titles, as well as ports and emulators.

Pirate compilations
As many Dreamcast games were much smaller than a CD's capacity, pirates have figured out how to make multi-game compilations. Where to get them? Hint, hint: RetroZone.co, Segahub, CoolROM, DopeRoms, Rom Hustler.

Atomiswave conversions
After discontinuing the Dreamcast, Sega still had bucketloads of parts. Rather than throw it all away, they quickly conocted this arcade system that was basically identical except with cartridges instead of optical discs. Years later, some hax0rs figured out how to convert Atomiswave games to the Dreamcast. You can find them here.

Important note: .gdi files cannot be burned to CD. You will need an ODE to run those on an actual Dreamcast. Only a few were converted to .cdi files.