Same thing happened to me. When I tried to create one, it changed automatically to 24 hour without telling me. I sent in a support ticket to ask about it. I had created a 4th speed game but dropped it- not sure if that was supposed to count.
This program, speed games for non premium members has been stopped starting this month. The result of having this as compared to when this was not yet implemented had produced very little difference that it was decided to just go back to when it was before - speed games for premium members only. If you want to continue enjoying playing speed games, you can always upgrade your account into premium.
Perhaps after some time, this will come back again or we will give you yet another better program than this.