To continue a bit rantish post at https://forums.elementalgame.com/385785

Leveling up

What is wrong with current leveling - you get practically nothing in return. The whole point of level up is that you are waiting for next level to get some ability and then immediately use it. Abilities should not be overpowered though - D&D, demigod, HOMM (to lesser degree) have very nice level up.

Elemental also has this concept in there, except for units. When city levels up you get immediate and very obvious benefits. When you research something (civilization level up) you also get something immediately. When sovereign levels up you get 1 ability point or something similarly useless. Ugh?

Here is an idea how this could work. Max level is 20. Level progression would look like this (should be fixed for balance, but you'll get an idea)

2) minor feat + 1 ability score + hp

3) minor feat + 1 ability score  + hp

4)  major ability boos (4 ability scores) + hp

5) major feat + hp

6) minor + hp

7) minor + hp

8) ability + hp

9) minor + hp

10) major + hp

etc

Ability score change of 1 currently doesn't seem to have much effect. If that changes +1 ability should be removed. Movement is *not* counted as ability when leveling up (we don't want movement rate of 25, right?)

The biggest potential in elemental is that you could play game in many ways. This should reflect in leveling up. You could have a couple of feat groups. Feats would have prerequisites (min. level 5, previous feats,...)

Groups with samples 

Governor - applies to city where sovereign currently resides

Small feats:

+1 gold in city per sovereign level

city trains veteran units

large feats:

50% more research (lvl5), 100% more (lvl 10)

Emperor - per empire bonuses

small feats:

+1 gold per marketplace

large feats:

each city +2 research

Personal - benefits sovereign only

 small feats:

+1 movement in forests

+5 attack versus spiders

-1 mana for fire spells

large feats:

+1 movement (maybe +2?)

+ special combat ability (smite evil, force strike, whatever, possibly free, see some D&D prestige classes for more ideas)

+ 50 HP (large number)

damage reduction, evasion, invisibility

no penalty for dying

free dragon

etc, it is not hard to come up with many many feats.

The point is that at the end you could create killing machine that could by himself defeat armies (e.g. Meteor swarm versus Goblins) or you can end up with emperor that cannot fight but has economy that powerful that nobody can touch him/her.

Not sure you have enough time to implement this though