Oblige Random Map Generator
...or 2000+ Maps Tested and Passed!
Tested by Blake Wilfong and Bryan Shelton
Article by Blake Wilfong
April 17, 2011


An impressive vista from the mind of a machine.

What could be so amazing that it brings the Co-op Certification Laboratory out of a decade of silence? Nothing less than a random level generator that adds the holy grail of gaming--infinite replayability--to the great-granddaddy of first person shooters, DOOM! A genius named Andrew Apted has crafted exactly such an application, called Oblige. It's the best random map generator we've seen, and it's free!

Bryan and I gave up on DOOM and other FPSes years ago when newer games stopped supporting co-op play and the communities for older games no longer turned out enough maps to satisfy our voracious gaming appentites. (Co-op has recently returned in a few games like Left 4 Dead, yet even those are repetitive, with only a handful of maps compared to the infinity of Oblige levels.) But thanks to the miracle of Oblige, we're back to playing DOOM, and we might very well continue for the rest of our lives.


Say cheese, Bryan.

In about one minute, Oblige generates an entire 32-level megawad for DOOM II. And, surprisingly, the levels it cranks out are pretty good. On a five-star rating system, we give Oblige-generated levels three stars--the quality of a fair-to-middling, albeit perhaps uninspired, human wad author.

That's miraculous. Because co-op DOOM, like pizza, is very good even when it's just average. And because every level Oblige generates meets all the Co-Op Certification Laboratory's criteria for being 100% co-op friendly. And because there's no end of new and different maps for us to play. Why hunt around for wads that might stink or poorly support co-op mode, when Oblige can generate a pretty good one almost instantly? The convenience is unbeatable.


This decorative, inaccessible courtyard is one of
the many finishing touches that keep Oblige levels interesting.

Indeed, we have played well over 2000--yes, TWO THOUSAND!--Oblige-generated levels, and we're still enjoying them. It seems likely that we always will.

To the best of our knowledge, no one but Mr. Apted has ever accomplished such a feat of infinite replayability. Other random map generators we've seen or heard of for FPSes, RPGs, and MMOs are primitive by comparison, merely slapping together prefabricated rooms or tilesets to build a map. Oblige constructs its rooms from basic components such as lifts, stairs, cages, doors, windows, balconies, etc., thus achieving limitless variety. Adding detail and interest are numerous prefabricated objects like crates, consoles, fountains, landing pads, bookcases, and collapsed ceilings, as well as the standard decorations including trees, columns, torches, and barrels that are built into DOOM.


Randomly created: A building with windows.

Oblige also generates puzzles--secret areas, keyed doors, and switches, and these can be built recursively to create puzzles-within-puzzles (e.g., get the key to open the door to reach the switch to lower the bars). And there are themes, like tech bases, caves, dungeons, and outdoor areas. Lighting varies as well; many a Spectre has ambushed us in dark hallways.


A faraway Hell Knight tempts me to do some
long-range rocketeering that would make NASA proud.

Oblige's randomness constantly makes us adapt and solve tactical problems. For example, the other night we stumbled across a Cyberdemon in a confined area and ran for our lives; with no room to strafe, we'd be blown to bits in a straightforward, toe-to-toe battle. But I eventually found a balcony that gave me a clear line of sight across a courtyard and through a window to the Cyberdemon. With that much distance, I could launch rockets at Cybie and have enough time to dodge his return fire. Before long, the beast was dead, with no casualties on our side.

Level size, amount of ammo and health, number of puzzles, and quantity of monsters are all adjustable, but we find most of the defaults to be excellent. The only change we make is to generate "hordes" of monsters, since having lots of monsters is fun in co-op play.


A bit of weirdness at the edge of the world. No biggie.

Never once has Oblige failed us. Each of the 2000+ maps we've played was finishable. The only bugs we've encountered were trivial cosmetic issues with texturing or weird appearance at the very edges of a map. Are you really going to notice, when you're getting slapped by a Revenant? We wish all commerical games were as solid as Oblige! Every level is fun, and some are particularly outstanding. I've included screenshots from several throughout this article.

The version of Oblige we use is 0.97, the last release before a radical change that doesn't suit our taste. As far as we can tell, the newer Oblige version 3 uses prefabricated rooms, more like conventional map generators, and has big, open, empty spaces instead of the delightfully detailed and claustrophobic worlds of 0.97. No problem, the older version is polished enough without any further development.


The start of another new level, never beheld by human eyes.

Oblige 0.97 can generate maps for Wolfenstein 3D, DOOM, DOOM II, TNT Evilution, Plutonia, Freedoom 0.5, Heretic, or Hexen, but our favorite of these games by far is DOOM II. For DOOM II, Oblige creates a secret exit on map 15 that leads to Wolfenstein-themed maps 31 and 32. Oblige utilizes no other map-specific features (like the all-mancubi-dead trigger on map 7 or the monster spawner on map 30), which is fine with us. Cyberdemons may appear on any map, though they are rare. Spiderdemons are nonexistent.

The Oblige home page is at oblige.sourceforge.net. We use Randy Heit's excellent ZDoom port to run the game on modern Windows 7 computers and play over the Internet. Its home page is at zdoom.org. You also need a DOOM2.WAD iwad file to play. If you don't already have one, you can buy DOOM II from Steam, nab a used CD-ROM on eBay or Amazon, pirate it quite easily if that's your cup of tea, or use the legal freeware substitute Freedoom, available from www.nongnu.org/freedoom/. Other developers have continued tweaking Oblige 0.97, calling their modified version ObHack. It is available from samiam.org/slump/. Several of the improvements (such as Capture-The-Flag maps and better Deathmatch support) are of little interest to us, so we haven't gotten around to trying ObHack ourselves. Those seeking historical perspective can also check out Slige, an earlier DOOM random map generator by Dave Chess. Alas, though Slige's maps were co-op friendly and impressive for their day, they lacked the complexity and variety to maintain our interest for very long.


Like any proud artist, Oblige signs its work.

Bryan and I wish to express our thanks to Andrew Apted for Oblige and Randy Heit for ZDoom, and all who assisted them. You gave DOOM back to us.

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