Humans are an inherently violent species. We have had more wars, battles, and arguments over the stupidest of things than I could list if I devoted my entire life to the task. Let us assume that SpaceX succeeds. Overwhelmingly. Some sort of technological breakthrough shortens travel time between Earth and Mars to a few weeks. By 2150, 25,000 people live on Mars in 5 different colonies.
The colonies have formed their own governments, though they pay nice, lump sums to SpaceX in exchange for new technology. The colonies are each independent of each other and of Earth, though. Say colony X discovers a rich deposit Unobtanium. Colony Y has a need for this Unobtanium, but all attempts at negotiation have failed. The prices Colony X demands in exchange for its Unobtanium are too exorbitant. As a matter of fact, since Colony X is sooo unreasonable, Colony Y has decided to loot...err, liberate, the citizens of Colony X from its tyrannical despotic government.
It must be assumed that treaties are in place preventing a single colony from legally destroying another, and that to do so is considered a war crime. To bring assault rifles and grenades against a Martian colony is a good way depressurize large parts of the colony and kill most people in it. Violence in space is dangerous, so what is the best way to be violent (best being the avenue that provides the least risk of complete or near complete annihilation).
The colonies were designed to be extremely modular. Essentially, it is comprised of many small living quarters (maybe the size of a bedroom) surrounding a central habitat (where the crops are grown, the government is located, the prominent citizens live, and where supplies are distributed from)
The requirements of the war are to avoid as many unnecessary civillian casualties as possible. Anything that will wipe out an entire colony(or a majority of it) is prohibited. There are some underground complexes, but they are nowhere near large enough to shelter anymore people than 500 or so. One small addition also; humans still rely on projectile weapons, as ' "Star Wars blasters" are unrealistic for the time frame we are talking about.
I am asking in general what weapons would evolve to meet the requirements set forth by the situation posed by warfare on mars.