Atari's Pong inspired lots of clones and spin offs, most notably Atari's own Breakout, which went on to become almost a genre in its own right. One of Atari's other variations on the same basic concept was Warlords. The game combined Breakout's block breaking with the four-player action of the rare 4-player Pong follow up Quadrapong and dressed it all up in a medieval theme. The idea is simple, you take control of a shield and have to protect your castle walls (I'll avoid saying rampart for obvious reasons) from a fireball, which is kindly donated by a dragon at the start of the game. When you deflect the fire ball it cascades around the screen and will hopefully take down one of your opponents' walls, unless they deflect or even capture it, in which case be prepared to defend yourself. Once a gap has been made in a castle wall, the warlord inside is exposed. If a fire ball hits a warlord it's game over, however there's no reason why a skilled player couldn't indefinitely defend a warlord with no castle walls - although a skilled player probably wouldn't end up in that situation in the first place.
The machines came in upright and cocktail form factors. The upright version supported up to 2 human players and actually used a mirror with overlays to give the otherwise basic black and white graphics a colourful and detailed look. However, the cocktail version (pictured right) is the one you want. It used simple colour graphics rather than the overlays, but it supported 4 players, each with their own corner of the machine. And Warlords is one of those games that gets exponentially better with more players. It's a great party game, especially if you decide to play in teams, as it's really hard not to accidentally bat the fire ball at your team mate. Warning though, many expletives may be uttered during the course of a game of Warlords, so those of you who are sensitive to curse words should bear this in mind.
The game also uses paddle controls, so it's another classic that does not play well on MAME. Not that you should be using an emulator to play any games and in the case of Warlords it was re-released a couple of years ago on Xbox Live Arcade and PlayStation Network with updated graphics and comical goblin characters running around the battlefield. Despite that, here is someone playing it via MAME and doing a hell of a lot better against the CPU than I ever could.
(UPDATE: 8:05, 02/12/2013) Turns out there were two versions of Warlords on XBLA and PSN. The first was one of the many Atari updates by Stainless Games, it included both the original 4-player game and a graphically enhanced version, with a future sport sort of vibe. The other was more of a remake, which really played up the medieval fantasy theme, complete with goblin minions and dragon riders, all beautifully rendered by a modern graphics engine. It also added new game modes, including a one-on-one versions of the game. Of the two, only the Stainless update is still available (and it's this version my kids and I have been playing for this article). Shame, because the remake looked really cool in the trailers back in 2011.