Here is the full list of all 15 Epic Little War Game achievements.
Complete the single player campaign
Promote any unit to Sergeant
Destroy a Behemoth Tank with a Grunt
You must destroy 100 enemy units
You must destroy 1000 enemy units
Win 10 Skirmish battles
Win 100 Skirmish battles
Take out 200 enemy units with Snipers
Destroy two enemy units with one shot
Destroy three enemy units with one shot
Destroy five enemy units with one shot
Win 10 Online battles
You won 100 Online battles
Win 10 Co-op battles
You won 100 Co-op battles