This drama is unfortunately one of the biggest disappointments I have had in a Korean drama in years, including the ones I chose to drop midway.
I have to admit I decided to watch it ever since news came out of the casting, because as a fan of both seasons of Stranger, I have come to admire Cho Seung-Woo greatly, and was excited for his next project, and for this reason solely, I didn't hesitate to watch, and for the same reason I kept pushing through no matter how frustrated I became with the drama.

Sisyphus is a scifi futuristic drama years in the making, boasts a high production cost, and casts a great ensemble, so what went wrong you ask?

while the production budget aided in creating hollywood-worthy looking scenery thanks to great CGI, and insuring rich cinematography, making the drama come out sleak and eyecatching, but alas the core element of any drama was deeply flawed; the story.

It was a drama whose creators may have well utilized a big production budget, but ended up focusing more on the visuals, and losing focus on what matters the most which is the story, and the cohesiveness of the science fiction plot.

While I admit the premise of the drama is original and cool (time travelling back in time to prevent a war and save the country), the story at its core turned to be a mess and plagued with plot holes, incohesive sequences, unexplained rules, and above all the science behind time travelling if any provided was illogical to say the least.

It goes without saying that any scifi media that discusses time travelling or time bending elements in many cases can prove to be a bit complicated and even sometimes dizzying to watch. But a neatly weaved plot and well written script that establishes a set of cohesive rules to the science behind it, are the key to help the viewer follow along. But in Sisyphus' case, especially during the second half of the drama when the plot finally started shifting from all the meaningless cat-and-mouse-like action phase and started to focus more on the time travelling aspect and the mission to change the past, the scenario in many times ended up creating more questions than it did provide answers, and even when it did provide answers they came too late, were sometimes unconvincing and other times downright illogical.

First, let's discuss the directing and general pace of the drama.
As I mentioned earlier the first half heavily leaned towards elaborate action, featuring a lot of car chases, gun fights etc. Although most of those (especially the post-apocalyptic future scenes) were craftly made and it showed the huge budget and amount of dedication put into creating them, I found myself feeling detached and not interested most of the time. The cinematography was top notch with many of the action sequences relying on sophisticated camera angles (using drones etc) fast moving shots, and wirework, but unfortunately like many other things did in this drama prove, too much of a good thing is not always to the better.

Proof to that, is how the writers time and again chose to assign precious airtime to slow-building action sequences in the future arc, that do little to the story's development other than maybe shedding a bit of light on how the Female Lead survived the harsh distopian post-war Seoul and came to learn to fend for herself, which many times unfortunately felt dragging and a distraction from the present day arc, and created problems in the pacing of the drama.
Or how, for the sake of creating catchy frames and thrilling action scenes, they chose to make everyone fire live ammunition at each other, even though the plot stresses on the fact that one side needs the other alive at all costs....and don't forget to mention that during such shootouts the leads rarely ever get hit, and if they do it is just a graze or a small cut to the arm, but the enemy always falls dead!

Second issue that made the show difficult to enjoy was the characterization, especially that of the antagonists, which was to put it mildly a total train wreck.
First off, the arch nemesis; Sigma, who was supposed to be the ultimate evil criminal mastermind who causes the demise of a whole nation, but who in reality ended up feeling like a silly cutout villain straight out of a comic book. No matter how I found him silly and laughable I always wished the writers had in store a strong background story to explain his grand agenda, but alas it was all just a childish and immature loser's grudge, soooo frustrating.
Also the Control bureau were just so incompetent and dumb watching them was a cringe-inducing ordeal that eventually required major adjustments to my villain-worthy standards.

Now to the main issue at hand; the story.
To end up watching a Scifi drama with half your brain occupied trying to wrap your head around what the hell anyone; both protagonists and antagonists alike; is trying to achieve (with all the gun fights and assassinations you no longer understand if they wanted him dead or alive?), or how a villain's warnings from a physical point of view make no sense whatsoever (kill me and my minions no longer look after your brother who is in limbo thanks to me existing?!!!!) , then It is not an issue of a sophisticated or smart plot, it is simply an issue of an ill-written plot.

There was a constant sense of incompleteness about everything regarding the plot, starting from the simplest and most basic of points (what was Quantam & Time intially selling that made it such a high stock company with a CEO fearured on the cover of Forbes?) to more pressing questions (what circumstances turned Sigma & the control bureau into allies and why?) To most fundamental matters on which the ending depended (If the uploader is never created shouldn't all time travellers from the future vanish simultaneously and not in such a convenient delayed fashion? Also wouldn't travelling back in time a couple of mere minutes ago to save oneself create an unescapable time loop?) And on and on...

The more you watch, the more you find yourself rolling your eyes at the caricaturish villains, and the more interactions you see between the leads and the villain, the more you scratch your head in wonder is it meet or the writers who do not fully comprehend the concept of time travel and the consequences of changing the past on the future?

All in all, Sisyphus may have been a fun to watch in terms of visuals and production, but the more you dive deeper the more you will get disappointed. I started to seriously wonder why such stars chose to take on such a project, and if they had received the full script before shooting started?
This is a drama that gives proof to the old adage, Not all that glitters is Gold.