Take a look at Quad Core: A frantic co-op space shooter that started as a university project.
Myself and friend recently finished university with Quad Core as our final major project. It was graded at 100% and felt it was by far our best work yet, so we've decided to take it further. Players are tethered to a shared Core, similar to that of 1986s Thrust. In order to move effectively players must work together and communicate.
Team decisions have to be made super fast in Quad Core as you can see. Our proudest feature is how players upgrade. The idea is that anything you manage to defeat you can become entirely. So if you and your squad manage to beat a tricky enemy with tonnes of HP you can equip its weapon, body and thruster (which all handle different stats).
Feeding into the upgrade system we've been working on a lot of different weapons. Here's the Bubble Gun (above) that you can fire at your friends to protect them for a short time. We are really trying to build weapons that promote teamwork as well as just offensive weapons.
When things get a little too much you can unleash the Core's blast! All players must agree to pressing X at the same time and then BOOM!! The enemies are eliminated! As you progress through the game different Cores become available. One Core freezes all of the enemies in place, while another makes all players invincible for a short period.
If you're still interested in the game, yesterday we uploaded the first full trailer to Youtube (https://youtu.be/wqDLy96U1Mc). As fresh graduates we have no funding for the game so we're hitting Kickstarter at the end of the month so that hopefully we can quit the day jobs and stop shelf stacking!