There should be categorization by intended use, such as 1st person shooter, MMORPG, RPG, RTS, etc etc. Its hard to tell what each engine is used for. \\^\\^"
Most engines are more general than that. Very few of them can only be used for one game genre. I think this would add more clutter than useability.
an "in practice" list may be useful though. A list saying which games have used the engine in question, if any.