Here is the full list of all 17 Sun Mystery - there are Playtest achievements.
Play a game
Win a game victory
Play a card to cause 200 damage
Play a card to receive 200 armor
Win a game on Standard Mode Difficulty 5
Win a game on Standard Mode Difficulty 1
Use the Shennong character to win a game
Use the Shennong character to win a game on Standard Mode Difficulty 10
Use the Nüwa character to win a game
Use the Nüwa character to win a game on Standard Mode Difficulty 10
Less than 6 cards in the deck and win the game
More than 20 cards in the deck and win the game
Restore 50 health points in a battle
After winning the game, have 1500 coins
Unlock lv6 Sky Map Reward
Kill a boss within 3 rounds
Play 100 games