[klodolph]

Which games? To my knowledge this is at best exceptionally rare because there are only ~114 CPU cycles in a scan line. The reports I've heard are that if you do any OAM changes mid-frame, you get something like four lines of glitches. More common is to just do a full OAM DMA during vertical blank, at least from the ROMs I've seen.

[marshray]

I can't find the original link where I read about this, it may have been more theory than about specific games. These links seem to be relevant: http://wiki.nesdev.com/w/index.php/Sprite_overflow_games http://forums.nesdev.com/viewtopic.php?t=16299