Day Wishing

[milo]

He perched upon the window seat.
His nose against the glass to peek
at children playing games across the street.

I would try "as children play across the street" for meter

He wished he wasn't such a freak
so friends would offer him to play,
convinced that he would win at hide and seek.

"so friends would offer him to play" is convoluted. Maybe "so they would welcome him to play" or something along those lines.
For the last line you could try "convinced he'd win at hide and seek".

He pictured every sun-filled day
if Mother wasn't such a prude
and knew just what his dad would say:
to drop the sulking, wishful mood-
polite young vamps can't play with food.

Maybe quote dad "just drop that sulking, wishful mood" though wishful feels wrong, maybe wistful or something. Of course then the previous line would need to be "and he knew what his dad would say"

Overall I like it. Did you consider making it a terza rima?(then I would like it even more)