Ha ... as I write this, I am just taking a break from transforming my dining room onto a Horrible Halloween Hell ... got ghoulish wallhangings from some online merchant, will utilise red Christmas lights, made cutouts of moons, witches, cats etc. As for games - may I recommend, highly, 'Make a Mummy'. You need a biggish pack of toilet rolls, and everyone wraps everyone else up in the tissue to make 'Mummies'. Much hilarity (and mess). I've tried this with budget toilet rolls but unfortunately these tend to disintegrate as one rolls up the 'Mummy' - I found Andrex the most fit for purpose!
As the little one and his guests are only four or so, nothing too frightening. My lot play Apple bobbing, Pass the Parcel, Musical Chairs (mind you, during one Musical Chairs my son, 40ish, got concussed), Statues. One game for when the guests are a little older is 'Guess What Horrible Thing This Is ...' Kids one by one are taken into a dark area, blindfolded, and their hands dipped into stuff - and they're asked what it is - then told! 'Eyeballs' (jelly), 'Guts (cold cooked spaghetti or tagliatelli - canneloni is an elegant variation, being 'big guts'), 'Pus (cold custard), 'brains' (cold cooked rice), 'bones' (some of those bone shaped dog biscuits), 'severed finger' (cocktail sausage)
My grandchildren, five of them, ages eight down to eighteen months, absolutely adore this particular Halloween game (OK, the eighteen month old is a wee bit young for it yet) and have for months been begging me to make sure it's included in my Halloween party itinerary.