In Space Clash: The Last Frontier, four galactic empires fight for domination of a system in a distant future. Besides its Command & Conquer-like real-time strategy gameplay, trading and diplomacy is an important part of the game.
There is a non-linear space campaign with a special space mode where you build space ships, fight, trade, move troops and attack planets in real time. You can choose one out of four races at the start, each one has different strengths and weaknesses. At the beginning there is only one planet on the map to attack and only a few vehicles can be build, more planets and units become available with further conquests. Unit types on a planet are ground, naval, amphibious and air, whereas each type can attack any other. There is also a race specific bombardment super weapon.
Buildings and units cost money. Money increases permanently but faster when mining raw materials, and with owning a lot of territory. When moving a unit over free territory it belongs to the unit owner, if no building is near. Your high command offers money for an amount of stored raw materials periodically and random units for money. It is possible to trade raw materials using a transporter, or to make peace and alliances with another faction on the map. Sometimes you have to pay for a peace treaty, sometimes you get money for it, if presented.
The objective of normal missions is to destroy all units and buildings of the enemy or buy all their possession at once for a high prize, your decision. Between the numerous standard missions there are 12 special missions with specific objectives like defending specific units/buildings or escape with a group of units.
The linear campaign is simple concatenation of missions, with the same maps of the space campaign in a specific order and without any background story.