Space Travellers

It takes place during the Earthlings' campaign against rebels, pirates and other security-threatening criminals from outside the solar system.
Ignoring the first mission, which is more of a tutorial of sorts, you start with a small ship with no ability to train new units (i.e. make ships). However, the missions are fairly simple, so you quickly go from a frigate named TS Spear to a destroyer named TS Dreamer. With this, you'll already be defending some space bases a few times, which will allow you to mine asteroids and build new ships in their facilities.Towards the end of this version of the game, you'll get to the TS Kraken cruiser, which you'll use to blow the rebels in the asteroid belt to smithereens.