Based on the rating here and elsewhere, I went into this with low expectations. It'd be fair to say they were blown out of the water. This is a really original and captivating sci-fi that does a tremendous amount with what is clearly a low budget. Unusually for spanish cinema, it's understated and not at all gratuitous, both very appreciated in this case. This is really worth watching for sci-fi fans out there. Give it a shot.