This is an absolute treat, though it's the least favorite of the three horror games I played in Barcelona (See spoilers below for why). I'd volunteered to translate for our group (only Spanish was available for this month), but the GM surprised us in turning to perfect English when he saw only two of us could speak Spanish - I wouldn't count on this working so bring at least one Spanish speaker and have them go first if you think you might need it :) )
Outline had the best set of the three rooms, with also the single best puzzle of the three, although it's disappointingly inconsistent in puzzle quality (NightShift and La Posesión have much better puzzles overall), and some of the puzzles make 0 sense in this world.
Outline is far less intense than I had expected (but with 6 people it's unlikely you'll ever be "alone" when jumpscared - you can always bring a friend along and go in twos or threes) - so, if you want a true horror experience, perhaps try it with 3? :)
It is less intense than La Posesión and maybe a bit more than Night Shift (but Night Shift will have more touching). I was touched twice in Outline - once as a surprise and once in a situation where I had plenty of warning (you could say I volunteered for it...), which is a lot less than I expected. One person gets "stuck" in a very "touchy" situation (IYKYK), and this is NOT volunteered... so be ready! I often went "first" in the exploration and volunteered to be the "lucky volunteer" twice where I expected to be touched - one time it happened and the other it didn't (the game's trailer gives you a hint as to what the "big split" involves - this is also the standout puzzle!) One teammate had her hair pulled back in an intense actor interaction, which went too far for her, and I was touched during the same moment. The standout puzzle is excellent for the "lucky volunteer" and terrifying for everyone, though it is absolutely boiling for the volunteer (me). Try to go in Winter... September was too hot for me and others in this international group, and you will leave many Barcelona escape rooms drenched in sweat (not to mention covered in dust... the dust does NOT add to the experience.)
MINOR SPOILERS
One big bummer which made this my least favorite of the three horror games: a really mediocre last third of the game that could be found in any tertiary escape room market with a mix of likes and dislikes. There's a puzzle which is impossible to see due to low lighting and small text, and we solved it only using some guesswork. There's a color-based puzzle which makes green, black and blue look identical and, when asked, the actor told us "that's intentional because if we had more light, then the puzzle would be too easy." (I did think of asking: what about making an actually good puzzle? :) ). The entire third could be cut (with the exception of the last 2 minutes - very fun), or it should be reworked and/or sped up (maybe by providing more light so you could skip through it), and it would be a much better game.