So you could spend a ziggityzillion dollars for decent seats to Cosi Fan Tutti. Or you could head over to Grindr the Opera and pay $20 to see an opera about gay men’s adventures with the titular app. Erik Ransom’s Grindr is part of Underscore Theatre’s 4th Annual Chicago Musical Theatre Festival, which includes six new musicals and two workshops. The material is eclectic, covering everything from Civil War-era feminists (Iron Irene) to escape from the Khmer Rouge (The Butcher’s Son). If you like new tuners, this fest’s for you. Through Feb. 25 at the Greenhouse Theater Center, 2257 N. Lincoln. Tickets are $15-$20; visit CMTF.org.