Start by reading the FAQs in the sticky posts. A lot of good information which would apply, even if it isn't specific to someone from the architecture field.
If you want to be a game designer, start by designing games. It's never been easier to pick up a game engine and start using it. Failing that, you can try designing board games. You want to build a portfolio that shows that you can do the work, in one of the hardest disciplines to break in to.
There are so many different ways in which people break into the game industry, it's impossible to tell you which will work for you. Are you surrounded by game studios? Maybe you can find work as a game tester and work your way up the ladder.
Are you signed up for the Global Game Jam? Maybe you can make connections there that will lead you to your first job.
Is there an amazing game design program you can attend nearby which will give you the skills game studios are so desperate for they will help you relocate?
Working as an architect might give you a slight advantage as an artist or level designer over someone completely clueless, but there's still a huge gap between what you learned and the skills game studios need, so don't expect this to be an easy transition, but you never know if you never try or give up too soon.
Best of luck.