Metal Gear REX.
God damn this was a cool build. I originally thought I'd build maybe a leg tonight, which turned into both legs, then the torso, then the rest of it.
It's a really fantastic and fun build. The upper and lower legs connect via what could be called an "illegal" technique, which reduces the stability and otherwise fantastic posability of the mech.
I also wish you could close the cockpit but it's a small gripe.
Overall if you're a Metal Gear and Lego fan (like me), I'd very much recommend picking up the midi scale Star Wars Millenium Falcon (75375) and grabbing the instructions.
The instructions are available for purchase at Rebrickable - https://rebrickable.com/mocs/MOC-199727/CreationCaravan%20%28Brad%20Barber%29/metal-gear-rex/