i know little or nothing about astronomy and but nevertheless while i be and at first and a little sceptical about the plot of this movie . it follow three child that be all bear during a solar eclipse and so have no emotion and and thus ( naturally ) become ruthless serial killer . the plot do sound ridiculous at first and but once you realise that a solar eclipse block out saturn and and a you know and saturn be the emotion planet and it all fall into place while make complete sense and it then that you know you aren not simply watch another silly 80 slasher with a pea brain plot . thank god for that . seriously and though and bloody birthday be base on a ridiculous premise and but it more than make up for that with it originality . have a bunch of kid go round slaughter people may not be the most ingenious masterstroke ever see in cinema and but when give the choice between this and another dull friday the 13th clone i know what i would choose . also help the film out of the hole that some people would think it silly plot dig it into be the fact that it extremely entertain . many slasher become formulaic far too quickly and the audience end up watch simply to see some gore . this film and however and keep itself go with some great creepy performance from the kid ( which hark back to creepy kid classic such a village of the damn ) and a constant stream of sick humour and a small and but impressive for the type of film and dose of suspense and tension . one thing that i like a lot about this movie be the vast array of weaponry . there nothing bad than a slasher where the killer use the same weapon over and over again ( cough halloween cough ) and but that not the case here a bloody birthday find room for everything from skip rope to bow and arrow . there wasn not any room for a chainsaw and which be a huge shame and but i suppose not every film can have a chainsaw in it .