Test drive 4 Easter Eggs

To enter these codes:
Go to the Save Game Menu.
Scroll down to Slot 10, Type in these codes and hit Enter.
You can type these codes in one after another.
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NOAICARS no AI in a lane game
BIRDVIEW ... more

1. start td4
2. go to save game option
3. go down to slot 10
4. type "creditz" (no quotes)