Proxis is definitely a great league thus far, and definitely NBT-light in many ways (which can be both good and bad depending on your preferences).
- planetary restrictions on some planets (limits to strikes, weapons, whatever)
- significant production limitations (thus "scarcity")
- limitations allow for a much wider use of non-meta mechs, contributing to differing strategies etc
- dynamic market pricing for mechs based on demand
- differing faction types (pirate, IS House, Clan, Mercenary) with significantly different reward systems and scoring conditions to determine who is "winning"
- no clear set end-game as it's meant to be largely on-going
- a limited sand-box map
Proxis doesn't have:
- lore adherence...there are faction types, but you are your unit, not a faction in the NBT sense. For example, there could be multiple CGB teams, who all choose to be Clan based (impacting their rules, rewards and victory conditions), but who are completely unaligned and fighting themselves.
- a full or accurate map...the map is enlarged as teams enter the league (or shrunk as teams leave); the planets are from the Inner Sphere for fluff and fun, but not accurately positioned necessarily or placed too seriously spatially. For example, our Clan Star Adder team has Turtle Bay as it's primary starting planet.
- robust, multiple layers with different game modes to represent the different stages of a planetary invasion, or a raid, or the various "steps" common to NBT. Fights are best of three, single map (determined by the planet) and that's largely it. Seizing a planet is based simply on attritting a garrison to below 12-mechs to fight with.
All in all it's a fun diversion from the more grognard-y gamestyle of NBT. It's very accessible, although they are still working on adding all of the rules/mechanics to their website. It's not as well laid out/explained as NBT or MRBC.