This is what Portal could have been like if Valve had failed miserably!
Skip that and pop into the game and you find a pretty funky gameplay idea... one hand has the power to push, the other to pull. Sort of Jedi like. You go through some basic puzzle stuff in the first/tutorial level which are pretty straightforward, and a couple are actually thought provoking enough for 1st level encounters that you can see the potential of further exploration... and then when that tutorial phase ends, very soon after, you reach a certain puzzle... or at least I did, which was infuriatingly delicate.
The problem with this puzzle ran like this... go down into an area that can kill you at an uncushioned drop (you can use your push powers to save you from death at the last minute.. IF you have of that psych energy left). Do whatever you have to at the bottom to enable you to achieve your "turn this thing on" purpose to get back to the main game path and then go back up.
Now.. getting back up is the problem. Where you have to jump to has a partial obstruction nearby which means it is highly likely you will be blocked and bounced back just as you figure you should be making safe contact with a solid walking surface again. Clearly the jump has to be exactly perfect. It's a puzzle that could make you feel good about achieving once you figure out the goofy little nuances you were overlooking the first few tries to finally figure out how to reach that particular ledge/surface.
Here's the exact problem.... when you bounce back, you fall to your death, since you had to use your powers to make the leap of faith in the first place... no chance to save yourself in a last ditch move (or at least, I never managed it). Each time you die, you reload back to the last checkpoint, which means you not only have to repeat all the crap you did at the bottom, but you have to do some other crap before you reach the puzzle pit again too. And each time you make an attempt in this system of Trial & Death you have to waste time redoing the puzzle over and over just because the last bit is so very precise in how it wants you to land, or land crouch, or....
I never figured it out, because instead of thinking about what I might be doing wrong with the puzzle, I started thinking about what I was doing wrong with my LIFE playing this game. Maybe it was death defyingly obvious and I just wasn't in the head space to figure it out... but this imposed grind to solve would should have been a simple jump went well beyond the point of no return. This game became a genuine chore and it really has no redeeming qualities to make you want to keep playing.
Even the reload time was abnormally long. Portal, HL2.E2 load super fast for me, the Crysis games on extreme everything loads nice and fast... this Twin Sector made me wonder over and over what was so time consuming to load/reload into the memory? Seeing as this is built on the Source engine that worked so well for HL2 and Portal, it boggles the mind what this thing needs to number crunch... yet another elaborate way to piss you off when you have the misfortune of wanting to try their puzzles again???
To sum up, Portal was barely a game. Great idea with an entertaining story that managed to last longer than the core mechanics involved "should" have allowed for (be honest, that's what it was... a core gameplay idea that they skillfully milked for every last drop of "fun"). Twin Sector is a variation, minor evolution even, on what is essentially the exact same gameplay mechanic.... and it is the entire execution of this game that make it as big a failure as Portal was a success, in all the tick boxes.