As outlined by cenGii91:
Open a small river map with only 2 players. There should be 5 artifacts. Collect them as quick as you can, get them to an edge of a map and build walls to protect them. After that just let the timer run out. Your enemy shouldnt do much.
Create a Custom Single Player Game.
- 2 players
- Game Mode: Random
- Map Type: Rivers
- Map Size: Small
- Reveal Map: All Visible
- Victory Type: Standard
- Difficulty Level: Easy
- Speed: Very Fast
- Extra Settings > Allow Cheats
To add on to the solution above, use cheat bigdaddy
(Enter, type cheat, Enter) to spawn fast cars that will allow you to travel across the map easily.
Set your Diplomacy (hands shaking in the top right corner of screen) to Ally for the other player(s). This will make your units avoid attacking the other player(s). On Easy difficulty, the enemy will not likely attack you.
Once you find the artifacts (carts that are moveable), move them back to your Town Center. Be mindful that if your cart passes too many of the enemy, it will become theirs. So strategically move around them, or bring one of the bigdaddy
cars with you for support.
When you have captured all artifacts, you will be notified with a countdown in the top right of the screen. Get that to run down to 0 years remaining, and you will win the game, achievement should unlock.