Sumeria is definitely not 5th tier.
Epic Quests is worth much more than 4/10 because you'll clear way more barb outposts than anyone else.
War cart is 10/10. You can rush anyone and take out any civ before they can do anything to protect themselves. You get the +100% prod to heavy cavalry card to make them faster, too.
Ziggurat is so so.
Adventures of Enkidu is bad in SP. In MP it's your chance to have an ally instead of rushing him early on.
Overall, late game depends on early game. There is no penalty to a large empire, and Sumeria should be twice as large as their second neighbour because noone can prevent them from killing their first neighbour, since everyone else needs research to get decent units. Maybe Egypt could survive? Scythia definitely can't (saka archers come too late).
Epic Quests is worth much more than 4/10 because you'll clear way more barb outposts than anyone else.
War cart is 10/10. You can rush anyone and take out any civ before they can do anything to protect themselves. You get the +100% prod to heavy cavalry card to make them faster, too.
Ziggurat is so so.
Adventures of Enkidu is bad in SP. In MP it's your chance to have an ally instead of rushing him early on.
Overall, late game depends on early game. There is no penalty to a large empire, and Sumeria should be twice as large as their second neighbour because noone can prevent them from killing their first neighbour, since everyone else needs research to get decent units. Maybe Egypt could survive? Scythia definitely can't (saka archers come too late).