04/29/06: THE MAIN EVENT
DOIN' THE OLD SOFT SHOE
Bombs impact the ground in much the same way -- if one lands in soft soil (sand, marsh, shallow water) there's a good chance it may not explode. Other bombs may be duds no matter where they land (earlier-era bombs are less reliable than modern bombs). At that point, the unexploded bomb becomes an unstable, possibly hidden (there may be a crater), hazard and could detonate if a monster steps on it, something damages it, or even just at random.
RE: MAINS OF THE DAY
Each time the map is loaded, the game engine decides which gas and water mains will be active, so it's not the same every time you play the game. When a gas main explodes, it creates a fountain of fire that rages for a long time. When a water main ruptures, a stream of water splashes up -- normally not hazardous except to monsters that fear water. Sewer ruptures spew, uh, well, you can probably imagine. Be glad your computer has no USB scent-emitting device.
SWEET MINES O' MINE
An optional monster special ability is X-ray vision, which lets the monster see all these hazards and avoid them. For example, the Giant Plant has "root talk": it can sense the presence of mines or underground hazards by communicating with its fellows in the plant kingdom through their "root network". Ed: This is apparently the same means by which my tomato plants tell each other to commit mass suicide every year before I can get even one &%$%* tomato.