Stock Simulator Question

I started a weekly stock simulator game at my shop for the guys hoping they might learn a little about money management. The rules are only...you can use whatever simulator you want as long as there is no delay in market price at order fill, any positive percentage greater than my own wins... winner decided at mkt close fri. The prize builds up on weeks with no winner so it has gotten up to $80 at a time.
One guy went up 38% in a matter of a couple of hours. He showed me what he is doing. He picks a low dollar stock (around $5) that is going sideways....ie up a penny....down a penny. He sets a $20k limit buy for the bid price then as soon as it fills he sets a sell at one penny higher...once it fills he repeats over and over. and in a matter of 15-20 minutes he was up 20%. I spent a couple of hours trying to duplicate this on thinkorswim paper and even let him try and we cannot make it work.

-is this a cheat? Or can you really do this and he just got lucky that it didn't drop 2 cents while he was doing it? I don't want to keep him from something cool but I know he wouldn't want to win with an unrealistic strategy. He is using the android app "Game of Stocks". I googled it and found nothing but I discovered it does have a delay so I will have to see if it is just a data delay or a real Mkt price delay.

I guess we'll just keep going the way we are. It sure doesn't seem realistic but I'm pretty new to all this myself and I don't want to cheat him out of something.

that can be very hard to duplicate in the real market because there has to be buyers on the other side. stocks that move sideways usually have super low trading volumes like 10K-100K The order wont usually execute unless the price goes up 2 pennies. If you buy at $1 and put a sell for $1.01, the shares wont sell until the price hits $1.02. Been there lost money lol Usually just the trade commission (lucky)

Ye, that's exactly what happens when I try to duplicate it on thinkorswim paper. Thanks for the input.