[citricsquid]

The best way to prevent any sort of manipulation is a combination of two things: have a "maximum conceivable score" and regulate the scoring server side. Every time a "round" ends (ducks on the screen) send the data to the server, compare the score relative to the previous score and if it's ridiculous (eg: the max score they could get is 500 and it's 10,000) you dump the session for being fake.

The obvious flaw with this is people who just work out what your maximums are and then get the 100% score, but it discourages the ridiculous scores.

edit: one of your people said this below, disregard :-)

[gridspy]

Also need to rate limit this, so you don't have someone playing an infinite number of rounds over 5 minutes.