Those are set numbers. Only thing that units are losing is their HP.
Game is really old. I've made it and played it with my friends around 1991-92. It had 7 races: New World Order (humans). Haots (mutated insects), El'ary (human-like mutants), Skorgs (non-human-like mutants), Teofides (mutated sea life), Omega I (robots) and Essencionids (aliens). I've added one more: Kaiju (enormous monsters) due to the watching of Pacific Rim. :}
I might add another chaotic mutant faction later, idk.
Story is: 2030 - 53 fragments of unknown comet fell on earth and released spores that mutated whole Earth life. From those new races were born and they started to wage war against each other. Humans fight to preserve old earth, while other races fight for survival or to conquer Earth for themselves. Aliens landed later (they were the ones that bombarded Earth with mutagen comet) to find out that their plan has gone wrong and instead Earth to be 'tera-formed' to suit their needs, it became a planet full of new sentient life (varsity of races). So they also started cleansing since they can't go back (their home-world destroyed).
So, we have humans that fight to liberate Earth from all new races, some mutant fractions that fight between themselves, robots that were initially made by humans to cleanse the Earth but gone rouge and now want to destroy everything and Aliens.
Kaiju just do whatever they like to do, destroy all in their path...
Interesting stuff when it's all mixed together and played.