@Ganymede
The Roguetech mod pretty much changes the gameplay. You get jumped to 3040 and it unlocks a lot of tech from that timeline era and opens up some of the early clantech options. In addition it has a lot more mech variants that are available for play.
It opens up the equipment lists to include Ferro Fibrous, Endosteel armor, and a host of other options for cockpits and fire control systems and other interesting pieces of equipment - including melee weapons.
The weapon lists include the Ultra versions of the Autocannons for that era, Streaks, you can get Guardian ECM and the Beagle Active Probe. Now the newest release actually includes Rotary ACs and some other 3060 era tech if you set your timeline to that era. But I'm not sure how that is done since I still have the version that are two versions past from the current version.
Lastly it opens up all the factions on the map and adds more worlds. Like a ton more worlds, more mission options, and gives you more of the merc experience for doing jobs, fighting for salvage, and supporting your favorite faction. It also includes a system that lets you flip planets to other factions if a planet is being contested and you do enough jobs in one system supporting one faction type.