Here is the full list of all 12 Ortus Arena achievements.
Play 50 games
Win level 12 in 8 turns
Win 7 online games in a row
Win 4 online games in a row
Win level 5 with holding 5 Wells
Play 10 online games
Win 2 online games in a row
Challenge a player online
Play 20 games
Finish the Campaign
play 100 online games
Play 200 games