Here is the full list of all 25 Gothic Playable Teaser achievements. It takes around 3-4 hours to unlock all of the achievements on Windows.
Finish the game.
Completed - The Fire Signal.
Completed - Some Meat as a Debt.
Kill 5 scavengers.
Open 3 locked chests.
Kill 1 snapper.
Completed - A Well Deserved Break.
Completed - A Decent Sword.
Collect 10 coins.
Kill 6 wolves.
Crush 10 meatbugs.
Build someone's trust in the Colony.
Completed - Medicines for Sarus.
Collect 20 blueberries.
Get your first magic item.
Collect 15 ore nuggets.
Loot a human body 3 times.
Survived the first night in the Colony.
Get your first weapon.
Heed nature’s call.
Prepare three different cooking recipes.
Investigate to the end a hidden mistery.
Completed - Orry's Headache.
Start a confrontation between creatures.
Barely survive a fall.