If he's got as far as touching and tickling you, he obviously feels comfortable with you, but that does not necessarily eqaute with any romantic interest. You should look at his eyes - does he hold eye contact slightly longer than necessary? Try holding his hand casually when you walk down the street - check his response. From these hints, he'll get the message that you are interested, and you should be able to find out if he feels the same way.
Come on Beenee you've been studing this area recently why don't you tell her what you've found out. Who can tell we're all different (lfe's rich tapestry and that) so there's no foolproof way of saying if he does this then......but you should find that he'll go a long way just to spend time with you or will change mood become more talkative (or less) when in your company. Hope it works out for you (and shame on you andy you'll have all those women in your house out for blood!!)