A mech game similar to Front Mission, XCOM, Pacific Rim, and... well, from there it's unique? Anyway, the idea:
You start in one of five "factions".
North+South America (Producing parts is cheaper), European nations (Producing parts takes less time), Oceania (Tech trees are faster to climb), Russia, China, Korea, and others (Can't think of anything o.o), and Africa, India, and the Middle East (again can't think of one).
Starting tech is semi-random, everyone has access to base technologies, then start techs get thrown about at random- each faction is guaranteed 4-6 starting techs, at least 1 of those being somewhat "rare".
Next, weapons and parts are generated based on your technology, anywhere from 6-10 designs of various costs.
Mecha building is one of the largest factors in-game. You can edit existing parts (bumping stats up or down for returns- bump them down for lower costs, or shift stats around to get a part closer to what you want) or build a new one. Either way, you can access newer technologies, updating a series of parts you really like allows you to keep a signature style.
Weapons building is similar- change stats and edit from a base or build anew.
Once you have a design, you can build one, build four (a "platoon"), or build multiple platoons. The benifit of building multiples is that if one is destroyed, you have more, and bulk prices are cheaper and less time-consuming.
Alternatively, you can export the completed product or even the design to another faction for extra cash.
Fighting is fairly easy- a regular transport helicopter can hold 4 mecha. You can upgrade your helicopters depending on what tech you've got, upgrading how far they can fly, how many mecha they can carry, or how many you can send at a time without the enemy micro-Kaiju noticing and trying to shoot them down (some have ranged, so... yeah. Risk three loud helis, and you might lose two (and eight mecha) before the fight even starts.)
You can't have your cake and eat it too with the helis- a quiet chopper group that lets you send 5 at a time with guaranteed success will not be able to hold more mecha or go very far.
Tech trees also net you other things- put enough research in mech design, and you can start building Mobile Weapons (Much larger, angrier mechs. Also less humanoid by a wide margin). Put enough research in areas such as avionics or such, and get the ability to call in strikes mid-battle. Put enough research into ammo types, and gain all sorts of bullet types to counter the Kaiju. There's many tech trees to fully follow, but you can't go down every branch and every one in one playthrough.
Time is directly influenced by what tech level everyone is at. Era I is mostly calm- humanity is brave and has little to fear. Era II brings stronger mechs to fight stronger foes, and humanity feels it's first tremors. Era III is the beginning of the end- the first miniboss appears, and many are lost in the first fight. Humanity is reminded of what they're up against. Gen IV is the struggle- mechs have caught up and the fight against minibosses is turning, but more minibosses keep coming. Gen V is the fall- it's you or them, and they've brought Godzilla to the party.
The factions start out mostly separated, but friendly. Near the endgame, larger (still not Kaiju size) beasts start emerging, factions start taking losses, and the globe bands together against the larger beasts. You'll get various bonuses depending on who you got to like you, and lead up to the final boss of a Kaiju-sized Kaiju.
You're still in like 7m tall mechs at that point, by the way.