For two players only. (Other numbers of players in future versions perhaps.)

Play in your web browser here with Unity web plugin.

Use WASD / Arrows or joystick/gamepad primary stick to control boat.
Use left control / right control or gamepad button 1 (hold it for a sec) to boost.

Two boats tethered to one battery. Neither can reach their destination without the battery, or with the other boat. Attempt to take out your opponent while guarding the power buoy from harm. Cooperate with your adversaries as necessary to protect it. Or, use it as a threat to deceive them into playing into your hands. When you've got them in the right position, pull them into the rocks with the tether or ram them with a boost.

Move carefully. Waterfalls on the river will drop you to your death on the rocks below, and the current moves ever faster...

You can yank your opponents with the tethering cables or ram them with the boat. A basic scoring system (it goes to 9!) is implemented but the game doesn't have an end unless you exit it.

Technical note: Doesn't use Unity physics engine, so it's well-behaved.