Pros
I've been involved in a few start-ups in my life ; I like having the chance to work in fast paced environment, having input into technical and business decisions, and not feeling like a suit is directing my movement. Riot is an established company that feeds those needs for me. This review is skewed toward that perspective. Riot has a very flat organizational structure. Regardless of your title you're expected to provide input and go "above and beyond" the basic duties of your job. There are no "closed door" offices in any location I've visited. The president and CEO have the same size desk as everyone else and sit amongst developers and producers. They make themselves available to anyone in the company to chat with. Although many employees have been here "since the beginning" I haven't seen any sense of entitlement amongst them; everyone is humble and appreciative that we're growing as a team. Outside of my technical duties, I've gotten involved in the community with Riot. I've had chances to attend conferences and seminars (GDC, E3, local entrepreneurship events), work on a couple internal "level up" initiatives, participate in collegiate events, attend hackathons, and work on some PR ideas. None of these things are in my job title, but I'm interested in it so the sky is the limit. Finally on the decision-making front... Riot has a bottom-up culture that values employees making decisions instead of management dictating them. I feel like my opinions and matter and are taken seriously.
Kontras
Riot attracts "Type A" personalities. Your ability to verbalize your goals and set a direction for yourself might not be for everyone. If you're a strong introvert who can't make an argument for a technology or idea you will be easily drowned out. There's technical debt to pay down. Much of the debt was created during the "just get something out the door so we can survive as a company" days. It's slowly being paid down but don't expect the cleanest code everywhere. That's probably true of many companies though.