Crossy Road

Play as Fortune Chicken or XI. Collect 10 red envelopes that appear on the ground. This can be done over multiple runs.

Swipe back and forth to move left and right instead of backward or forward when in the sandy median areas. Swipe back and forth a total of 100 times in one run to unlock the Crab. Swipe five to ten times when you reach a median, then continue before the eagle appears. If enough swipes were made, the Crab will be unlocked after you die.

Play as an Australian character (Kangaroo, Platypus, Echidna, etc.). The Drop Bear will appear randomly at the top of the tall green trees. Get within two squares of him and he will jump on your character. Although this ends the level, he will now be unlocked.

You can unlock most characters in one of two ways:

Spend 100 gold in the lottery to receive a random character.
Spend $0.99 in real-world money to unlock the specific character you want.

In-game gold is earned a number of ways. You will receive some as you regularly play, and you can find it in the field as you complete your runs. If you like, you can even watch short ads to receive additional gold, so there's no need to ever spend real-world money if you're patient.

Play as Festive Chicken. After scoring 50, 100, 150, or 200 points, you might randomly enter a large clearing. Run next to the giant Christmas tree in the clearing and it will explode, dropping with presents and coins. Complete the level and Gifty will become unlocked.