Level 3
Level 3 is a legacy War.app single-player level from before the campaign overhaul in 2016. It introduced cards and the Earth map to new War.app players.
Details
The level is 1v1v1v1 on the Earth map. Unlike in level 1 or level 2, player and AI's starting positions are random. This means that it can be useful to re-start the level a few times to find a starting position that you like.
Gold stars are awarded to players who complete Level 3 in 19 or fewer turns (25 on the standalone client).