Another meander around ModDB reminded me that I was rather taken with the idea behind Bramblelash [official site]. It's being billed as a multiplayer party game where you and a friend hold either end of a length of bramble and use it to clobber your foes.
From the gifs and description it's basically a game about navigating obstacles and clotheslining things with nature's barbed wire: the bramble stem.
At the moment developers Bytesprite are working on adventure mode - "a series of discrete single screen levels that are varied in a number of ways in order to further explore the central co-operative tether mechanic". What they're describing is a set of levels with escalating difficulty interspersed with boss fights.
Also planned is a versus mode for up to 4 players and online multiplayer.