Liar Game is a relatively short drama with effectively 11 Episodes à 35 minutes runtime. It basically amounts to 5-6 episodes of regular korean drama lengths. This means, that your time investment in this show isn't as high as for most other dramas. Taking that aspect into consideration, Liar Game is a successful show in giving you the enjoyment for your invested time.
The story is innovative, but lackluster. It has nice mysteries but definitely isn't groundbreaking in this aspect. For all ya'll folks who watch anime, you know what I mean. There are titles such as Akagi or Kaiji and they clearly surpass this type of story depth. Now that we've talked about the story strengths and weaknesses, let's focus on the main and best point about Liar Game: the acting. Especially Akiyama (Shouta Matsuda) and Fukunaga (Kousuke Suzuki) come to mind as being greatly presented. Hasegawa is another strong point in the story aswell as being well presented by the actor Kinya Kitaoji. On the other hand, there is one big weak point in this and sadly it's the main actress of Erika Toda representing Nao Kanzaki. Her character, which can easily be put in the jar "useless as it is", mainly meets one purpose: Representing the "dumb" and inexperienced viewer in this story so the writers can easily combine these two parties and give the viewer an "identification person" in this story. As many other shows do this, this doesn't seem that stupid at first, yet Erika Toda acts this so poorly and the writers especially lack using the key point of identification, which this character brings. All this leads to it being very frustrating to watch this drama all through out and even if the viewer doesn't understand every single aspect of the mysteries and puzzles presented, he/she can be sure that Akiyama will come to rescue to save the day and that Kanzaki will never once solve anything by herself. Except one example in the revival round, where she finds a way to make everyone happy, Kanzaki clearly lacks intelligence and empathy for her situation she is in.

Therefore, if characters are really important in a show for your own enjoyment, i suggest NOT watching this drama. If you can easily oversee stupidity and naiveness over and over again without any learning done by the main character aswell as her poor actress representing her, then go ahead and enjoy the about 6 hours of 7,5/10 story.

More in-depth review: https://youtu.be/foNCXs6o2x0