Here is the full list of all 35 Dead Island: Riptide Definitive Edition achievements worth 1,000 gamerscore.
Obtain level 70
Find all collectibles
Find all the secret files
Find all the volunteer's voice recordings
Find all pages from the guide book
Finish all quests in the game
Kill 10 monsters with one mine
Finish the game
Complete all the main quests cooperatively with any number of partners
Defeat Harlow
Enter the docks in Quarantine Zone
Find 50% of collectibles
Make pact with Serpo
Finish quests for Dr. Kessler
Kill 100 monsters using the boat's speed boost
Kill 100 enemies using charge attacks
Survive the horde on the roof
Finish hospital quests for Cecil
Find and kill all the most dangerous monstrosities located in dead zones
Gain access to a long-range radio station
Kill special enemies: Grenadier, Thug, Wrestler, Infected, Suicider, Screamer, Butcher, Floater.
Clear out the cinema
Obtain level 50
Reach Henderson
Kill the Twins
Successfully defend the tunnel entrance
Rescue 20 NPCs that have been grabbed by monsters
Install a total of 5 barricades during hub defense
Kill 100 monsters with thrown melee weapons
Mark 100 opponents which were then killed by your co-op partners
Kill 25 monsters with a chainsaw
Kill 50 monsters by smashing, decapitating or shooting them in the head
Find a boat for use in the jungle
Kill 100 monsters with a kick
Escape from the ship