Make possible seen the lawn in the plant selection

A preview of what the level looks like would be very helpful, especially since there are squares that can't be planted or other gimmicks, some plants may be more or less efficient depending on the shape of the lawn.

I also think it would be cool if it were like PvZ and PvZ2, where zombies also appeared (even though they're already in the selection screen), this brings back something cool from the old games and adds more immersion.