The original Q.U.B.E. is like an 8/10 for me - pretty good with some neat secrets and a cool ending (which the Director's Cut kinda ruins by basically revealing it early on).
But the Director's Cut is more like a 6.5/10. They added a pointless story (imo, no puzzle game needs a story - you came here for the puzzles, not some deep lore. Even the Portal series is still fun without the story), didn't even add subtitles for it, removed sound settings, and made the game slower by adding long stretches where you just sit and wait for narration you don't care about to end. The voice acting is good though, so it's not grueling to listen to - just a bit annoying.
The story itself is written ok enough, but uses second person throughout the entirety of it - which is a pretty bad way of writing in general, as it creates a disconnect where the character does one thing, but the audience goes "wait I wouldn't do that, why's it calling me out like I did something?" and tune the rest of it out. This game does try to make it work by framing it as one character lying while both claim to be telling the truth, but this is funny cube puzzle game. I don't care about the story. I just wanna do cube puzzles.
In addition, I'd warn completionists to stay away from this as the "Against the Qlock" DLC levels have some of the stupidest, most pointless filler bullshit achievements I've ever seen. It's just "beat the dev times" and "replay the game 50 times" which aren't fun or interesting to earn (unlike finding the secret picture of the devs and/or finding each beta level) - and having speedrunning in a game designed around the opposite of that is such a massive disconnect that I am genuinely stumped as to who tf thought it was a good idea in the first place. Thankfully, the tenth anniversary edition realized this and fixed it - so I'd say to play that if you want to 100% the game.
But, the main campaign is quite fun. It's got some interesting mechanics and level design, and is generally a fairly interesting couple hour jaunt through a bunch of cube-themed puzzles.
My only complaints are the inclusion of a story, the ending to said story not implementing most things from the dialogue, the game starting in 1024x768 (which the OG version also does), and almost all the graphics settings being turned off by default. Also, there's only 1 sound slider whereas the original game has 3. Not sure why they removed the others...
I'd recommend you get this and play the original version, or just buy the tenth anniversary edition. Buying the Director's Cut gives you both (but not the DLC for the first game? Even the Ultimate Edition bundle doesn't have it... bit odd), and the DLC is just kinda bad imo. Fast paced speedrunning doesn't work in a slow paced puzzle game, and the power-ups they give you to do them just feel so out of place. The art & lightning is also greatly improved here, making everything look a tad nicer than in the first game.
3.0