Complete campaign mode and Challenge
then play with AI

the trial time will run even if you're at menu i think
maybe you can play with very easy ai coz if play campaign the cinematic/movie already eats up a lot of the trial times

Click single player and there should be "Play against AI" button at right side
then just wait for the maps to load
select a map then go next screen
select computer AI you want to play against
then start and glhf with the AI

you must have original version