All you need to stop a brain is a bullet.
30 generic problems to dole out for homebrew, custom made, and scratch built machines
The walking siege engines of the Cosmic Era
The Rocky Mountain Republic owes in large it's existence to a single limited run of primitive mechs, the Assault/Bombard Mech model 1.
Technology in the Cosmic Era can become corrupted and infested. When this happens to a mecha, the result in codenamed a Hekatonkheire.
The home base of the mighty mech
The reasons that mecha are not reliable as weapons of war are manifold, but the world changed more than many people expected and the way wars are fought have changed greatly since the middle of the Petroleum Era.
A common light mech of the Atlantic Federation
The ultra minimalism mech, for the common consumer
While technically alive, magnagogs have little in the way of personality and are driven via telepathic command.
The Sogans were a mystically aware technological society. Queen Stavarang is the last surviving Sogan in the galaxy
In a crowded marketplace, a man is standing on a soapbox, orating. Some of the crowd are cheering, some hissing, some standing around saying "I can't hear a bl**dy word he's saying". It's a hustings for an election. The PCs can either leave, or stay and listen. If they do the latter, then they can vote too, and they might get quite involved in the cheering. Depending on who wins they might get quite involved in the post-election brawl too...
There are numerous possibilities with this encounter: the PCs might end up talking to one of the nervous candidates before their speech, and offer encouragement and support. Of course this candidate may well turn out to be someone with outspokenly unorthodox views, and the crowd don't take kindly to s/his supporters. Or maybe the seemingly innocuous candidate turns out to be a complete racist, and the PCs wander off embarrassedly, pretending they weren't talking to this person five minutes ago.