Here is the full list of all 55 Watermelon Game achievements.
Combine 1000 Lemons
Combine 1000 Cherries
Get a Multiplier streak of 20
Get 1000 Points in a single Match
Combine 1000 Strawberries
Upgrade your first Fruit to a Golden Fruit
Get your first Golden Fruit
Use your Skills 100 times
Combine your first Watermelons
Use your first evolve skill
Use your first destroy skill
Finish your first Game
Get a Multiplier streak of 10
Get your first Watermelon
Use your first power shot skill
Finish 100 Games
Finish 1000 Games
Get 2000 Points in a single Match
Get 3000 Points in a single Match
Get 4000 Points in a single Match
Get 5000 Points in a single Match
Get 6000 Points in a single Match
Get 7000 Points in a single Match
Get 8000 Points in a single Match
Get 9000 Points in a single Match
Get 10000 Points in a single Match
Combine 1000 Grapes
Combine 10000 Grapes
Combine 10000 Cherries
Combine 10000 Strawberries
Combine 10000 Lemons
Combine 1000 Oranges
Combine 10000 Oranges
Combine 1000 Apples
Combine 10000 Apples
Combine 1000 Pears
Combine 10000 Pears
Combine 1000 Pineapples
Combine 10000 Pineapples
Combine 1000 Honeymelons
Combine 10000 Honeymelons
Combine 10 Watermelons
Combine 100 Watermelons
Combine 1000 Watermelons
Combine 10000 Watermelons
Get 10 Golden Fruits
Get 100 Golden Fruits
Upgrade 100 Fruits to a Golden Fruit
Upgrade 1000 Fruits to a Golden Fruit
Use your Skills 1000 times
Use your Skills 10000 times
Play a single Match for 1h
Play for a total time of 10h
Play for a total time of 100h
Play for a total time of 1000h