Yeah for supersized mechs you'd be better off with games that deal with almost as much fantasy as science fiction. Something like Core command if you have it would love giant skyscraper sized space suits with lazors.
Or, dark heresy if you also want your mechs and pilots to be worshipped by peaseants and need massive gravity manipulation to stay together, let alone move.
But, the cultures that would want a small one man bipedal machine are there. I can easily see an Ihaetei loading a under 15 foot tall mech into his scout in preference to an ATV. It can be used for construction, war, and to mud wrestle giant predators. And with the right setup it'd be usable with minimal training, thus avoiding the Aslan male deficiency with technical subjects.
Plus..mud wrestling space dinsoaurs with killer cats in Votoms does sound kind of fun, but easily done as a serious thing as well.
As for landmates. Wouldn't those just be heavier versions of battledress? Slighty larger artillery versions to supplement the more human sized types we've already seen.