All of the characters in these new releases are characters from the Marvel comics universe, with the titles and characters for each set being:
• Unmatched: Hell's Kitchen, with Daredevil, Elektra, and Bullseye
• Unmatched: Redemption Row with Ghost Rider, Luke Cage, and Moon Knight
• Unmatched: Teen Spirit, with Ms. Marvel, Squirrel Girl, and the team of Cloak and Dagger
• Unmatched: For King and Country, with Black Widow, Black Panther, and Winter Soldier
Each of the games is playable as a standalone title for 2-3 players, and they can be combined with one another or with any other Unmatched release. Maybe Black Widow versus Robin Hood to approximate an intra-Avengers squabble with Hawkeye, or Daredevil versus Invisible Man from the Cobble & Fog set to pit a superhero who cannot see against a madman who cannot be seen.
Jayme Boucher at Mondo Games tells me that the exact release dates for these titles will be announced in the future.
Given the huge slate of new shows announced by Marvel in mid-December 2020 — including shows focusing on Ms. Marvel and Moon Knight — who knows which other Marvel characters might appear in Unmatched in the future?