That's a bold comparison, but I think it holds true. Much about the atmosphere and humor of this physics puzzler is either lifted from, or a loving tribute to the Portal games depending how you look at it. The major difference between Esper and Portal (besides the absence of literal portals) is that Esper takes place entirely in one room.
The review for the Oculus version applies apples to apples to the Gear VR version, as they are identical. Some minor cosmetic improvements have been made but you'll be hard pressed to spot them. The voice acting in this game is phenomenal. They got some really remarkable talent onboard for this. Every little vocal inflection conveys something about the situation or character speaking.
The puzzles are clever, too. Supremely clever. Not so much at first, but as the difficulty ramps up, the puzzles become positively mind-bending. The ingame rules governing ESP don't really make sense but are self consistent, and you typically learn them just before putting them to use solving a puzzle designed around that specific limitation. Similar to how in Zelda games, you obtain a new weapon or item in the same dungeon as the boss you will need it to defeat.
This game can be played on Gear VR without a controller. Passably even, it's just that well designed. But it's much less comfortable and natural than using a controller. Evidently many Gear VR owners are putting off buying controllers. For some reason, a $99 headset wasn't too expensive, but a $50 controller is. I won't pretend to understand consumer behavior. If I did, I'd be writing for Forbes, not Steemit.
The fact that you're confined to a single room throughout the game never really feels confining. You're seated in a chair which moves with you, giving you a high degree of immersion (unless you play standing). The whole room transforms around you, forming whatever new puzzle you're meant to solve.
The humor is top notch and legitimately funny. It's a little snarky and mean spirited at times, hence the comparison to GladDos. I don't laugh at just anything but was legitimately tickled several times. They have excellent writers over at Coatsink (the dev) on top of excellent voice actors. Both are serious strong points for this game, even though the gameplay itself is also excellent.
That's just the thing. It could have slid by on the quality of just the game. Or the quality of the voice acting and writing. But all three are great! There's literally nothing to complain about. It's not even that short, given that it costs just $5. This is some of the best fun I've had in VR.
Esper and Esper 2 are now sold as a bundle. I'll be reviewing Esper 2 tomorrow, but sufficed to say it's even better than Esper, which I'm giving a 9/10. If you have either an Oculus Rift or Gear VR, this is a title which absolutely belongs in your library.
Screenshots credit to Oculus and Coatsink