Cardboard Jam 2014 from 9 a.m. to 10 p.m. Saturday and Sunday at the Massachusetts Institute of Technology’s Building 32-124, also known as Ray and Maria Stata Center, at 32 Vassar St. Register for $20 (the event is free for MIT students).

Participants will form teams to make non-digital games using simple materials such as paper, pencil, cards and board. No experience is necessary – the weekend starts with an introduction to the Jam and game development and a few games will be played to help participants get to know each other. Facilitators will lead the participants through brainstorming and sessions that will help form teams at the Jam site. More information is here at the MIT Game Lab site.

Somerville Open Studios from noon to 6 p.m. Saturday and Sunday. Free.

The 16th annual Somerville Open Studios has more than 400 artists throwing wide the doors to their workshops and studios for public perusal and includes some group shows, including an Artists’ Choice Exhibit during open studio hours at the Somerville Museum (1 Westwood Road, Somerville) to which every open studios member artist was invited to submit one work of art, and a show of 15 first-time participants in the “Inside-Out Gallery” that can be visited at literally any time, since it’s in the display windows of a CVS (1 Davis Square, Somerville). There’s also a Volunteers Art Show at Bloc 11 Cafe (11 Bow St., Union Square, Somerville) from 7 a.m. to 8 p.m. each day and a Kids Art Show at The Center for Arts at the Armory, (191 Highland Ave., Somerville) from 8 a.m. to 6 p.m. Saturday and 11 a.m. to 6 p.m. Sunday.

Event information for Somerville Open Studios is here. An interactive map of studios and way to find artists is here. A version optimized for smartphones is here.

OnStage Arts Marathon starting at 6:30 p.m. Saturday at the Onstage Dance Co., 276 Broadway, Somerville. Entry is $10 Cover. (The show is 18-plus. There will be alcohol for those 21-plus.)

This all-night fundraiser for the nonprofit dance troupe turns its studio into a theater, comedy club and music hall celebrating the arts with two dozen acts in dance, music, improv, comedy and visual art (on display and on sale from Cristina Hajosy, Monkey Chow, Reed McLaren and Liza Pratt). Performers include the Cambridge Dance Co., Iconic Movement, Kinetic Synergy Dance Co., Nazar Bollywood Dance Troupe, OnStage Dance Co. and Phunk Phenomenon; Kate Brule, The George Woods Band and The Okay Win; Big Gulp, Dana Jay Bein, Sean Clarke, Disco Basement, Emily Lavadiere, Russian for Elephant, Dave Stern, Christa Weiss and Whale Heart. Information is here.

To get to the studio using GPS, use “278 Broadway, Somerville” instead of the actual address, 276 Broadway.

Brattle Theatre Tag Sale from 11 a.m. to 2 p.m. Sunday at The Brattle Theatre, 40 Brattle St., Harvard Square. Free.

The nonprofit Brattle Theatre has accumulated a lot of stuff over the years, everything from film posters to books and other ephemera, and for the first time staff have decided to sell off duplicate items and odds and ends that are too odd and endy for their their purposes. The event includes free snacks and the screening of some short films.

MayFair from noon to 6 p.m. Sunday in Harvard Square. Free.

This 31st Annual Mayfair features the usual overwhelming assortment of music and dance on four stages; more than 150 artisans and merchants selling arts and crafts, jewelry and vintage clothing; international food from more than 40 vendors, three beer gardens; and other entertainment for all ages, including Roaming Railroad train rides. Another favorite returning feature: The Chalk on Walk, a Church Street art event the Cambridge Rotary Club’s uses to raise money for local charities and scholarships. And Cambridge Historical Tours has transformed Winthrop Park into a free Victorian activities center for kids aged 2-10 and their families, including old-timey games and races, lessons in making a cornhusk doll or flower garland and dress-up from a costume trunk while being helped and entertained by costumed guides. Information and a complete performance schedule is here.

The WEMF Street Team Pizza Party at 7 p.m. Sunday at WEMF Radio, 110 Brookline St., Central Square.

WEMF Radio, a grassroots online radio station based in Central Square, invites listeners and performers to come in and talk about helping it become “the best local radio station in Boston.” Organizers invite people to starve themselves Sunday, show up to feast on their pizza and “come together to talk about how you can help WEMF be known throughout Boston and the surrounding areas. Help us grow this station by becoming part of a crazy-ass group of folks known at the WEMF Street Teamers.” Information is here.