I recently bought "Star Ruler 2".
Never played the first game, but I am very impressed with this one. It sort of mixes the trade mechanics from the Anno series (in a more abstract form) with Sins of a Solar Empire (real time gameplay, fighting to control systems), adds some planet improvement and ship design options like Star Drive and a tech web plus customizeable races with pretty big differences in playstile like Endless Space.
The tech stuff is pretty cool - 6 different FTL drives, Star Forges that harvest solar matter to turn it into production (until the star explodes...), Planet Buster ships, Shield and Cloaking technology, Artifical planetoids, Ringworlds - and that stuff is well integrated into the mechanics.
The game goes sort of like this: You start with a single homeworld and expand. You can level up your worlds, but each level requires more and more ressources. A planet has one ressource that it can use for itself or export to other worlds (by simple "drag and drop" of the planet on another planet on the map). That can be tier 0 stuff (food, water), which can be substituted by buildings (but that is quite costly early on). Then you have tier I and (very rare) tier II ressources, plus some very special things like "get extra FTL energy for each level this planet has" or "get more diplomatic influence".
Apart from just levelling up a planet, the tier I and II ressources also create "pressure", which the consuming planet turns into free civilian buildings that provide yields like money (used to build stuff), science (used for tech), enegy (used to activate special abilities or artifacts - from water comets to planet generators), diplomatic influence (used to buy and play diplo cards), defence points (used to get free defence ships) and production (used to - duh - produce things). So by creating special supply lines you can specialize you planets - and there is constant pressure to grab all the fancy worlds before the other empires can reach them. In addition to planets you have asteroids that can also have ressources or ore (which is used to build super powerful stuff like Ring Worlds or Star Forges).
Another really cool thing about the game is the diplomacy system. Instead of only the usual treaties you also have the "Senate". There is a stack of dipomatic cards that you can buy for influence points, slowly moving to the left, getting cheaper with each tick. Some of these cards are used to start a vote in the Senate, which can be basic stuff like "host a science center on my world" or "all players get vision on one race" - or you can lobby for the peaceful annexation of planets and even whole systems. Once a vote has started, everyone can play cards for or against the issue. There are also some special cards like: "If the vote passes you get a 'leverage' card that can be used against that race and gives an extra large amount of votes" or "If your vote fails you get the starting card back". And then you also have improvement cards like "Name Planet" (extra pop and production), "Name System" (fleets fight better), "Cultivate Food" (add free food to one world). And you can also use influence on a few key techs, so there is basicially always a struggle where you want to use this powerful but rare ressource. It is one of the most interesting diplomatic systems I have seen in a 4X for quite some time.
...I could go on, but why not just watch
Scott Manley's video about the game?
tl,dr:
A fantastic 4X game that brings a lot of cool new features to the table and is worth the rather low price of 20$!