When you play as a new character, the graphics will often change a little bit. Usually this will be limited to the scenery down below – for example, if you play as Pew Pew Pew it becomes the Wild West. If you play as Screech the Bat, it becomes red rolling hills. Graff will turn the entire stage black and white, including all of the enemies, but not including the treasure boxes.
If you pick up a blue gift from the inside of a blue treasure box, it will contain a gun upgrade that lasts until you die, or until you pick up a blue gift with a different gun upgrade. If you pick up an orange treasure box, you will get a wingman such as Gunny Rabbit or one of the pugs, which will last somewhere between 30 seconds and one minute.
Let your finger off of the screen for a couple seconds and your character will quit shooting. Instead, they will charge a shot. When you hit the screen again, they will fire homing missiles. You don’t have to keep your finger off of the screen for too long of a time in order to get the charge shot.
In fact, if you want to get a ton of charge shots in a row, tap the screen at a rate of about 4 times per second. Tap super lightly so that you can start charging as quickly as possible when your finger leaves the screen. You won’t be able to move around this way, so just move as needed to avoid shots, but you’ll kill every enemy on screen with all of your homing missiles (mostly).
Want to get your free gift immediately, right away? Go to the date and time settings on your phone or tablet and set the time ahead by six hours after you open a free gift. Then go back to the game, play, and die again. You’ll get an automatic free gift after that.
You can do this trick as many times as you want. However, once you set the time back to normal, all of those six-hour periods will be added back onto the free gift timer, so you won’t be able to get a free gift for awhile after doing this trick a number of times. Still, after doing it enough you will have so many coins that it won’t even matter for awhile.