lastly, another(player a bit maniac), uses the "knock down" token, use the catapult horizontally and launch the "bullet" in a rare to see velocity... destroy not only meeples but deplace some tiles!!!
I played the Catapult for the first time Wednesday night last week and we did the same thing. I see no problem with it myself (although displacing tiles is not good) as everyone can do it if they want (and it doesn't always work - most of the time the "bullet" would fall off the catapult when using it sideways instead of launching for me
).
We also angled the catapult at different angles rather than flat on the table and one guy put it on the ground to launch it onto the table.
I figure that it is an expansion set that I'd only play when I feel a little bit silly (rather than wanting a serious game) so messing around like this is fine if everyone is happy with it being done.
The alternative launch methods probably technically are house rules though as the diagram in the rules does show the deployment of the catapult as flat on the table (if my memory serves me correctly).
