Here is the full list of all 33 Midsummer Night achievements.
Collect antidote
Reveal bear's secret
Exit kremlin underground by the sound of the stream
Help the ghost find his parents
Help the Apple Tree
Find the dugout in the forest
Punch a one-eyed likho 3 times
Get to the Flooded island by water
Exit kremlin underground through the Red Chamber
Get to the Flooded island by underway
Step on a frog 3 times
Wait out an ancient deity awakening in a hidden place
Use squirrel to get the boat
Reveal Man's name
Find caves in the forest
Discover Dead Forest secret
Cross the river over the log
Cross the swamps
Complete the game
Listen to the story to the end
Give strength to the frog
Pull the merchant out of the swamps
Save the baby from starvation
Find the trail of the beast
Encourage peasants to change their attitude toward village elders
Spend 30 minutes in the game
Spend one hour in the game
Spend two hours in the game
Take 3 attempts to pass one of challenges
Take 9 attempts to pass one of challenges
Climb up the hill
Get even with the bear
Examine 4 sorts of flowers using Q key