To complete a level, you must clear all objectives that you come across and get to the end.
If you lose all 3 lives, you can retry from the last checkpoint (unless you return to the menu, after which you'll need to restart the level from the beginning).
If a checkpoint seems too difficult, you can skip it, but you need to make at least 3 attempts without returning to the menu in between.
As you play through levels, you will receive different objectives.
Match Colors Together

You will see ice chunks in 4 different colors: blue, green, purple and black. An ice chunk will only break if you throw it at another one of the same color. If it hits the wrong color, it'll just bounce off. When the pattern is done, you will receive a bonus based on how many correct matches you made. You'll need at least 90% correct matches to reach the best score.
Break Down the Big White Ice Chunks
You'll see one or more big ice chunks floating in the midst of smaller ones. They're too big for Squid Hero to grab, but you can break them down piece by piece by throwing the smaller chunks at them. If you hit the same big chunk many times in a row within a short time, you'll get a combo bonus. You will advance once all big chunks have been completely destroyed.
Turbo
Squid Hero turns on the jetpack's turbo mode! There's no ice to break here, but you must avoid hitting fences and other obstacles. Lean left and right to move Squid Hero. Keep your feet comfortably apart and your knees flexible!
Rescue the Animals
You'll see animals trapped inside ice cubes. They can't get out, and if they float down to the whirlpool at the bottom, they'll sink! You need to throw ice chunks at the animals' ice cubes to free them. Once an animal is freed, touch it once more to rescue it. If even one animal is lost, you'll have to try again.
Make a Hole
You may encounter a big shipwreck blocking your path. Here, you need to throw chunks of ice at the ship to break pieces off. You don't have to destroy the entire ship - it's enough to make a hole that Squid Hero can fit through and pass to the other side. If you ever get stuck behind, you'll lose and have to try again.
Avoid the Mines
Someone has scattered dangerous mines all around the river! They'll explode if you get too close. Your objective is to avoid getting hit by mine explosions. Unlike in Turbo mode, you can use your hands to move around freely.
Mayhem!
During Mayhem, lots of ice will appear all around you. Your objective is to keep smashing them at a steady pace. The faster you smash, the higher the meter will rise. Don't take too long to aim or the meter will fall! But don't clear the entire screen, or you'll have nothing to smash and keep the meter up. Once Mayhem is done, you will receive a bonus based on how high the meter was at the end.
Boss Fights
At the end of each of the five locations, a dangerous boss awaits. You must throw chunks of ice at the boss's weak spot. The bosses are smart, however, and will try to cover their weak spot. Look for openings and strike quickly. You must also avoid getting hit by the boss's weapons. Boss weapons will also destroy any chunks of ice that they hit!