AWS offers a free tier. This let me play with AWS on my own time gratis. I think GCE needs this... unless they have it and I'm just not aware.
As for the actual price... GCE's cost of .013c / hour is so tiny that I don't see how you can say it's a "huge deal".
You can spin up a GCE for 5 hours a day for a week to experiment and it'll cost you less than 50 cents. It's not quite free, but it basically is. As long as you're just playing around, always-on shouldn't matter so you can spin the server up to play, down when you're done, and thus pay almost nothing.
app engine is more like AWS beanstalk where as compute engine is more like ec2?
Maybe I'm wrong here.