A severely underrated arcade game from the early 80's, Mr. Do! (note the exclamation point) plays a lot like it were Dig Dug Deluxe: it is a game in which you dig your own maze and drop heavy things on enemies for lots of points. Ultimately Mr. Do! mister does... um... it is a good deal more complex, challenging, and ultimately satisfying than Namco's popular gardening game.
The best way to describe Mr. Do!, in fact, is to start with Dig Dug. Each level is a cross-section of underground terrain, through which you and your enemies can move around like ants in a farm. The level begins with a small number of passages pre-dug, but beyond that it's up to you to make your own. Digging is quite simple: whenever you move into an area that contains dirt, you automatically create a tunnel behind you. You're slightly slowed by the effort of digging, but a lot less than you'd expect.
Some more things that are like Dig Dug: scattered throughout each level are Apples (rocks in Dig Dug) that, if you dig out the earth underneath them, plummet down through all the empty space below, and even thin sections of dirt, taking everything with them. Also, each level ends once all enemies are defeated, and there are various bonus snacks to collect, like Pac-Man's fruits, which are worth more and more points the further you get into the game.
While there are actually a couple of more obscure ways to finish a board, the general object of each level is to either collect all the cherries (there are 40 buried throughout each screen, and you get extra points for grabbing eight in a row) or defeat all the red monsters, called "Badguys." (That's either the least or most original name for enemies in a classic arcade game.) Doing either one of those things will finish the board. Early on, collecting cherries is probably easier, later on killing all the monsters is a better bet. They come out, two at a time, from a spot in the center of the board. Early rounds have six monsters, but there are more in later stages. Once all the monsters are in play, the entry spot is replaced by the bonus item, which, unlike Dug Dug's vegetables or Pac-Man's fruits, actually plays a central role to the game's strategy.
One important difference between Mr. Do! and Dig Dug is in the way monsters treat the tunnels. In Dig-Dig, monsters will generally prefer to travel by tunnel, but if they cannot find an easy route to the player's location they'll "seep" through the soil. I like to call it "traveling by osmosis." While seeping they travel much more slowly, but aren't restricted to the strict horizontal and vertical movement everything else in Dig Dug (and Mr. Do!) must follow, including the player, and they're much harder to attack with the air pump. Dig Dug's Pookas and Fygars are actually rather apt to start travelling by osmosis, and it happens rather quickly in each board. On the other hand, Mr. Do's Badguys always follow the tunnels. After a while on each level some of the more frustrated monsters will dig their own passages, with a bit of flashy advance warning, but they still, always, follow the tunnels, either pre-existing, player-dug, or monster-dug. Mr Do's monsters, in an unobstructed area, are very good at tracking down and giving chase, and as they gradually gain speed as each level progresses it becomes very important to avoid well-connected areas, and to dig new tunnels with care.
Mr Do's prime weapon against the various monsters may not be as fun as Dig Dug's air pump, but it adds a lot of depth to the game. He carries a little sphere called the "Powerball," and with a button press it shoots out ahead of our protagonist clown, bouncing Breakout-style off of the walls up ahead (although no holes are made by its progress). One hit with the Powerball will kill any enemy it strikes, but once the ball is launched it cannot be quickly fired again. When the ball strikes a foe, it takes a varying amount of time for the ball to "recharge" and be used again. The first use on each board seems to regenerate quickly, after about a second, but as time passes it takes longer and longer to charge up, up to what seems like ten seconds of dead time. Since each level gets harder very quickly (few games last longer than five minutes of actual play time) this is a significant limiting factor. Furthermore, while the Powerball can be launched and left to roam the level unattended, Mr. Do is defenseless while it's off bouncing. The ball can always be caught by touching it, but it can be a lot of trouble to track down. A Mr. Do without a Powerball quickly becomes Mr. Don't – you should never let yourself be without it for long. The Powerball's recharge period seems to reset back to one second at the beginning of every board, and whenever one of the bonus items are collected.
Using the Powerball is tricky at first. When shot down a long shaft with no turns or branches, it is always well-behaved and will continue down until it hits one of those or a dead end. The occaisional turn likewise causes it little trouble, but zig-zags sometimes cause it to double back depending on its exact trajectory. Tunnel branches are bad news for Powerball use, as they greatly increase the chance it'll careen down an unwanted route and get lost on the other side of the board. The Powerball takes a while to recharge and can be unpredictable, but used properly it is sure and the primary way to kill enemies.
The Apples buried around each level are Mr. Do's other weapon. Again, they work very much like the rocks in Dig Dug, they stay in place until something digs the earth out from under it, at which point it will shake for one second then fall until it hits solid dirt, destroying any thin walls, monsters or careless players it strikes along the way. Unlike Dig Dug's rocks, they can also be pushed horizontally into open shafts, and if two Apples are situated beside each other, pushing one will move the other too. On the negative side, the Badguys have learned the same trick, and since they can create their own tunnels, they can also drop Apples that way (though they usually kill themselves in the process). To most things in the game, an Apple is an impassable barrier, but the Alphamonster and his guards can eat them, and are hard to kill with apples for that reason. To crush them, the Apple must be dropped while the monster is traveling horizontally. Both killed Alphamonsters and guards turn into Apples, which are usually either cannibalized by other guards or, if killed from below in a vertical shaft, should immediately be dodged before the gargantuan fruit crushes our plucky hero's body, flat. Oh, and dropping an Apple only one "space" on the board won't destroy it unless it lands on a monster.
The earning of extra lives in Mr. Do! follows a strange, almost pinball-like system, where the player must collect the letters of the word "EXTRA." These are earned by killing Alphamonsters, which sometimes emerge from their little "EXTRA" display at the top of the screen and wander about for a while, with a big letter on its chest. It is possible for Alphamonsters to emerge bearing letters already collected, which don't advance the player towards an extra life if killed, and because they needn't be killed to finish a level these are not worthy of attention unless they're closing in. When an Alphamonster isn't in play, it sits in the EXTRA box and cycles through the letters, lingering on uncollected ones much longer than those which have already been earned. When a monster randomly comes out it will typically be of an uncollected letter, but whenever the bonus item is collected, the one that appears when all the red monsters are in play, then all the red monsters will freeze where they are, and whatever Alphamonster was currently selected will parade out and start chasing the player, accompanied by three weird "guard" monsters.
One neat thing about Mr. Do!, and many of Universal's other arcade games, is that spelling EXTRA not only earns you an extra life and starts a special animation, it also instantly completes the level. Depending on circumstances, if you mess up in a later board and dig a few too many tunnels, it can occasionally be a bit easier to finish up EXTRA than trying to survive the remaining Badguys. Better yet, once in a great while a dropped Apple will break open to reveal a Diamond. These are serious prizes: they complete the level, are worth 8,000 points, and award a free game! (That last bit depends on operator settings.) Diamonds are very rare, but it seems like they come in runs. Most games you won't see any, but once in a while you'll get two on one credit.
A good strategy in Mr. Do! is surprisingly difficult to construct, and they often require that the player take advantage of the many little nuances of play. At the start of each level, the player can either collect cherries or kill the first two monsters with the Powerball, each of which can be accomplished without much difficulty. The ease with which the Badguys find Mr. Do depends greatly on how wisely he's dug out his way around the level. Long tunnels with few branches not only make it difficult for Badguys to catch up with the intrepid spelunker clown, but are also much easier to defend with timely use of the Powerball, and long vertical tunnels leading up to an apple can make quick work of several monsters at once. While this is going on, trying to kill any wandering Alphamonster is a good idea. Once monsters start to catch up with Mr. Do, or the Powerball recharge rate gets to be too long, or once the Badguys start digging, it's time to run and collect the bonus item and freeze them in place. Because the bonus item freezes the Badguys, can generate an Alphamonster which can be used to build towards an extra life, shortens the Powerball recharge delay, and is often worth bunches of points, it is one of the most important objectives in the game. This usually gives you a breather, as the emerging Alphamonster and his guard, while difficult to crush with Apples, start out at the slow start-of-level speed. Going after the Alphamonster can be dangerous at this point, as once he or his guards have been finished, the Badguys will unfreeze and be faster than ever. Instead, consider roaming around the board and killing them while they're frozen, as that will get you to the next board and its initially-slow monsters much faster.
Finally, the little things. Every three levels there's an intermission where the game recaps your progress, showing you how well you did in each level and displaying, with an icon, the way you completed it. (I wish I had a screen shot of that one intermission where I had two Diamonds!) After ten levels there's a special "Wonderful!" message that makes you feel all warm inside because it's damn hard to get to. There are ten different boards that cycle after you've seen them all. The dirt on each board has a different "texture," usually some variation of pastel with an overlaid pastel design. And there's the difficulty, which is really quite high. I can easily complete ten levels of Dig Dug, especially using the rapid-pump trick, while even three levels of Mr. Do! give me a hard time. Universal doesn't seem to have made many games of which I am aware, other than Mr. Do! sequels and Lady Bug (which is every bit as fun and challenging as 'Do). They are worth keeping an eye out for.