One of latest games I am really-really fond of, is QED (though it was just me, my friend didn’t enjoy it). From OPs list I’ve played Portal and Braid, and while those are visually interesting, they weren’t enough hard to make me happy. But QED had.
> Who developed it/What other things they developed It was written by Terrence Tao, a brilliant modern mathematician, exactly to explain math logic to layman.
> What platforms it is on/When it came out Purely web-based, completely free.
> If there are (good) Sequels/Prequels/DLC It had one sequel (FOL and predicates), which is now combined with main game.
> If you believe you finished it Hell yes! I finished it, and I liked that nowhere I had to lookup for solutions.
> How long is the game (how long it took you, NOT the number of puzzles) It took me two weeks, and quite a bit of thought.
> How difficult is the game, in general (you can compare to other games) It is of mixed difficulty. Overall it is hard, but doable. If you are a math student and it seems easy, then you may try to find optimal solutions. I think some optimal solutions were obtained with computer brute-force.
> How the puzzles fit into the Deduction/Efficiency/Technical/Linchpin categories All of these! The efficiency though is optional, personally I stopped searching optimal solutions after some time.
One of latest games I am really-really fond of, is QED (though it was just me, my friend didn’t enjoy it). From OPs list I’ve played Portal and Braid, and while those are visually interesting, they weren’t enough hard to make me happy. But QED had.
> Who developed it/What other things they developed
It was written by Terrence Tao, a brilliant modern mathematician, exactly to explain math logic to layman.
> What platforms it is on/When it came out
Purely web-based, completely free.
> If there are (good) Sequels/Prequels/DLC
It had one sequel (FOL and predicates), which is now combined with main game.
> If you believe you finished it
Hell yes! I finished it, and I liked that nowhere I had to lookup for solutions.
> How long is the game (how long it took you, NOT the number of puzzles)
It took me two weeks, and quite a bit of thought.
> How difficult is the game, in general (you can compare to other games)
It is of mixed difficulty. Overall it is hard, but doable. If you are a math student and it seems easy, then you may try to find optimal solutions. I think some optimal solutions were obtained with computer brute-force.
> How the puzzles fit into the Deduction/Efficiency/Technical/Linchpin categories
All of these! The efficiency though is optional, personally I stopped searching optimal solutions after some time.