Ravyne just hit the ones I was thinking.
Unfortunately yes, age discrimination is rampant. Some people interpret "culture fit" as "young white male", instead of "intelligent, creative, and passionate".
The good news for you is that studios with age discrimination also tend to be terrible places to work, with late hours, hard crunch, and poor work-life balance. Working at places where everyone has a spouse and children tends to mellow out the worst offenders, and encourage people to think about things like time off, insurance plans, retirement plans, and other benefits.
USE YOUR CONTACTS. You've got 10 years in the industry so you know people. Hopefully you've taken the opportunity to grab email addresses, facebook contacts, linkedin recommendations, and more. Spam your facebook account, google groups, linkdin account, and any social networks where your former co-workers work.
The number I've heard from recruiters, business web sites, and books like "What Color Is Your Parachute?" is that one hour of working your social network is worth about ten hours of spamming resumes and blind applications. That doesn't mean don't send in applications that way, but when you have a choice between the two prefer the more effective one. You have a much higher chance of finding a job. For me with a recent job change and far more than a decade of experience, I made a single facebook post with "Hey former game co-workers, I need a new job!" and within the day I had several interviews lined up. This works best if you live in a game development hub.
Make your resume specific for the individual job, and let them know you are flexible. If they're looking for a senior software engineer, adjust it for that. If they're looking for a team lead, adjust it for that. If they're looking for tools or gameplay, or build system, customize it.
The higher up you look, the smaller the pyramid. If you're focusing on senior positions and lead positions there will be fewer openings. Consider taking a lower job, and trimming your resume accordingly. Also, consider using recruiters.
While some places in the world have a custom of including every job you ever had in your life, other places just look for relevant stuff. Generally it is okay to let stuff drop off the end, and omit the graduation year if you want. Rename it to "relevant experience" if you wish.