Supreme Commander 2

Even if you suck at RTS games, like me, you can pick this one up very easily in under 15 minutes.

Set up a skirmish match against Easy AI on the Clarke Training Center map. (I chose UEF against Illuminate.) Being a 1v1 map, it's easier than taking on multiple AI opponents. Set the game type to Assassinate, and the rush timer to 10 minutes. Then start the match and get building.

When the match starts, use your ACU and Engineers to build two Mass Extractors and two Air Factories. When the Air Factories are built, set one to build a single Wasp fighter, and set it to Repeat Build (press down on the d-pad while in its build menu). Set the other factory to build an Eagle Eye bomber and Repeat Build.

Continue stockpiling aircraft while the rush timer counts down. I added a land defense turret and two air defense turrets just to keep my assets covered, and started adding more mass extractors to keep the air factories pumping out units. You may need additional Power generators too.

Once the rush timer runs out, gather all your aircraft (I had about 26 in total by this time) and send them straight into your opponent's base. Find his ACU and direct all units to attack it. I suffered only two unit casualties using this method and finished of the ACU fairly quickly.

Using this method will also net you the following Achievements at the same time if not yet earned:

Quicker method legit way.
Small 1 v 1 map

Illuminate vs UEF easy AI

First off start a game on a small map. Hit left bumper and research veterancy, build cost, and finally build time (Total research points is 8 I believe 2 for veterancy 3 for time and 3 for cost spend leftovers on structure build cost/training.) Begin by ordering engineers to construct 2 mass extractors, 2 energy generators, have your ACU construct the air base. Build up several fighter bombers and send them straight to the enemy ACU which is normally dead center of their base they should not have defenses but might have air. If done correctly you'll win the match in about less than 5 minutes.

Fastest method.

Just start a match on a 3 vs 1 map and add 2 cheating hard AI's to your team. They'll do all the fighting.