Inside is serious entertainment.
This game is beautifully designed with quite varied environment that makes expert use of lighting. At the beginning the main character is running through forest and corn fields, and the layers of parallax scrolling elements captures a great sense of depth even though player is just running and jumping from left to right. Very few colors appear but the occasional red and yellow focus attention on the elements that player must interact with to progress. Usually switches, handles, and puzzles are in red. Yellow cable hints where the secret device lives and player and decide it ignore it or follow the lead as these secrets are not required to finish the game.
The environment is so great, it contrasts the odd animation when the player-controlled character is moving, most obviously running. Especially in outdoor scenes, the character's footing feels a little out of place as he moves. Maybe the animation was designed to convey some other attributes.
There isn't a lot of music that I remember as I played through. But the sound design was remarkable especially when there is clear danger on-screen, and the game gives this neat audio queue that seems to drive me more anxious.
This game has a very distinct film-like texture throughout. Maybe it is the temporal reprojection anti-aliasing technique the developer open sourced. Perhaps it is the geometry design. Whatever it was, it looks great.
The player-controlled character becomes something else not human towards the end of the game, and it is just a pleasant and weird surprise to control this thing that is so unusual and unfamiliar to solve puzzles. There is something endearing in the thing, even though it has many visual qualities that repel me (like many other parts of this game, such as dogs mauling the main character, or body parts that comes off, etc.). Very satisfying when it goes through glass walls and doors.
At one point in the game the reality bends and really allow a different class of puzzle designs to be presented. Up until that point the puzzles more or less follow laws of physics; while that is good fun, it has also been done in numerous other games and solution is usually obvious so it becomes a chore just to trying to execute. But when you can have water that is unaffected by gravity it is great, and those are the puzzle elements I enjoyed the most.
There is a loading system that is very useful to revisit areas to collect secret later. It consists of a horizontal selection of dots denoting starting points of an area. As the dot is selected the screen fades to present a picture of what the area looks like, and if player confirms selection loading happens seamlessly in the background. It is very intuitive and low-friction. Not like the other games that show wait indicator in the corner of a loading screen with progress animation, where player is clearly notified that they have to wait through the loading screen, even though the same waiting is happening. It made me realize that players don't care if they have waited and completed 50% loading progress.
There must be a story behind all of this. Why is the boy running to the right? Is that really the end (it is just sunbathing and taking a nap, what...)? Many things about this game is left ambiguous. I think it strikes the perfect balance and keeps the game short, allowing me to finish it in one setting without feeling exhaused. But the environment and actions of non-playable characters clearly convey a sense of urgency to move player into the next area, and giving background with the settings (check points, laborartory, underground tunnels, etc.).
I come away impressed and inspired as Inside really shows the interactive power of telling a story well. Much to learn from a game that only requires a few hours to play. The time I spent playing Inside is the highlight of my week, so much fun.