You know, I haven't tried the DT770-250, but I find the 770-80 a good deal less fatiguing than the DT880. Different family yes, but that may help if you've heard the 880. I really don't think the -80 is all that fatiguing at all, and really quite enjoyable for gaming.
If anything its problems are:
Midrange somewhat recessed, but not so much as to destroy the music.
Higher register is somehow colored, the sounds provided don't really bear any distinct timbre of their respective instruments.
Bass can be a tad boomy at times.
But they're damned fun. I think most games were mixed specifically for THIS type of sound, honestly.