Ok so I just finished testing around 200 games
Good news is I only have found 5 games that do not work which I know are good rips.
basic the gist of my post here is that 99% of all dreamcast games will at least boot and are somewhat playable in Reicast. From my exp if u dont make it past the Sega logo then it is most likely a bad rip or you are using a scene release.
I am not going to elaborate on specific gfx issues for each game but have some tips for people struggling to get their games to work.
1. CDI files do work but if the if cdi is in caps then reicast will not recgnize it...needs to be lower case ".cdi"
2. Scene releases by Echleon and others who replace some of the games binaries with little songs and name plates instead of the default Sega screen will not work. I only had a few of these for unreleased DC games such as Half Life. Presumably if you fix the binaries then the games should work. I found a Half Life Rip that is unaltered and am going to test it shortly. I would link but it is against the rules
3. Almost every game works most all will make it past the dreamcast logo and sega logos. If that occurs and you get a freeze at say the games loading screen or the start screen then it isn't a rip issue it is an emulation issue. For example Gauntlet Legends works for me on NullDC on my PC but in Reicast it freezes at the "Gauntlet Legends Loading screen". The rip is fine and I tested my rip 3 different ways in both CDI and GDI formats and it made no difference. On the other hand if anyone else can get Gauntlet legends to work please let me know so I can look at my rip again but I am confident it is correctly done.
4. There are a few games whose screens go black after the Sega Logo but are still working : Omikron the Nomad Soul being one of them. I know the rip is good cause it works on NullDc and cause the sound and button presess in Reicast are working. Just some gfx issue with that game makes everything black (again if anyone has had Omikron boot in reicast please share how you did the rip with me)
5. Finally here is a list of games I cannot get to boot in reicast: Culdcept II, Psyvariar 2, Slave Zero, Starlancer. I believe the rips are good but they freeze at the Sega Logo so it may just be my rip or a compatibility issue that just stops the emulation at that point.