Timelines: Assault on America is a 3D real-time strategy game based on alternate version of World War II. According the game's story Hitler died and the Germans try to invade the United States. There are single-player missions, a cooperative mode and cross-platform multiplayer. The AI examines the player's style and attempts to adjust to the player's skill level.
The main currencies are tokens and money. Tokens are used for upgrades. In each level 17 are provided and in multiplayer one every 40 seconds. The main resource for buildings and units is money. By capturing radio towers 20 pieces of currency are earned per second. There are various types of infantry, tanks, cannon and trucks. Units have a visual range, a firing range and a certain amount of health. These statistics can be enhanced through upgrades, but these only affect units made after acquiring the upgrade. Buildings include a headquarters, a light factory, a generator, a bunker, a research facility, barracks, a radar, and a heavy factory. Gameplay elements include healing infantry, repairs, deploying minelayers, loading infantry in trucks, airstrikes, and detaching cannons. Units can be put in an aggressive or defensive mode.
There are 12 missions culminating in the battle for Washington D.C. Multiplayer is about destroying the enemy's headquarters and only the commander unit can construct buildings. It is player versus player, but also as cooperative games for up to four players working together, fighting the enemy AI. There are nine countries to choose from (USA, UK, France, Russia, Japan, Germany, Hungary, Romania, and Czechoslovakia) with twenty units per nation. Certain orders can be delayed to have them be executed in unison.