Experience

Experience (XP) Gain Rules

The unit that gets the killing blow receives 50% of the XP
Only kills from weapon attacks will grant kill XP
Fire, acid, skills, and hacks skip kill XP and instead distribute 100% of the XP via Participation XP

Any unit, including hacked units, that hits with their weapon counts as participating. Damage does not matter
Hacking, even partially, counts as participating
Ground effects do NOT count as participating
Summoned units tag their summoner as participating
Hacked units will slowly get XP for themselves from participation
Participation XP is split equally amongst all participants, rounded down
Participation XP is 50% if kill XP was granted, otherwise 100% of the total XP if the unit was hacked or killed by skills or ground effects

In the following situations, after XP is distributed, the XP that a unit would be granted is zeroed out

Dead units, all XP gains are negated. Except when a Rhino uses Final Blitz, it still receives XP from the exploded units
Summoned units, all XP gains are not retained
Hacked units, kill XP is negated. Participation XP is unaffected which means that hacked units slowly gain XP for themselves
Units at max XP for their level, all XP gains are negated
Units killed entirely by skills and/or ground effects grant no XP

Two Marksmen shoot each other. One bullet will hit milliseconds before the other which means one of the Marksmen gains 200 XP and the other gains 0 XP from being dead when their bullet hits.
A Vulcan summons a Marksman. The Marksman kills a crawler. The Marksman gains 6 XP, 4 from the kill, 2 from participating. The Vulcan gains 2 XP from participating via summon.
A Hacker hacks a Rhino while being assisted by crawlers that survive. The Hacker gains 200 XP. The Crawler gains 200 XP.
A Stormcaller with incendiary bomb leaves some fire on the ground. A squad of Fangs dies to the fire. The Stormcaller gains 0 XP since it did not hit the Fangs.
A Mustang hits a Rhino with Armor Enhancement and deal zero damage. An Orbital Javelin kills the Rhino. The Mustang gains 400 XP since it participated.
A hacked Rhino kills another Rhino that was partially hacked by a Hacker. The Rhino gains 100 XP via participation for itself, the 200 XP from the kill is negated. The Hacker gains 100 XP via participation.
A Rhino with Final Blitz is killed by a Rhino which is then killed by the Final Blitz. Both Rhinos gain 400 XP for killing a Rhino

XP requirements increase each level by a certain multiplier of the previous/base level. E.g. level 3 requires (XP to level 2) * 20 / 9