First you need a pet which is large enough to ride, not humanoid (exception made for Centaurs) and has a solid physical form (e.g. not amorphous like a pudding or whirly like a vortex). You must also be in a humanoid form and not too big or small to fit on a saddle.
Next you need to saddle the pet by applying the saddle to it; you need at least one free hand for this. It is possible to saddle a non-tame monster, but this is more difficult than saddling a pet, and you will not be permitted to ride the monster until it is tamed.
Now mount the steed with the #ride command. Unless you are a Knight, this will make it less tame and may untame it. If any of the following conditions hold, you simply won't be able to ride for obvious reasons:
- You are already riding
- You are hallucinating
- Your legs are wounded
- You are stressed or worse
- You are blind and not telepathic
- You are punished
- You or your steed are trapped
- You are levitating and cannot come down at will
- You are wearing rusty or corroded body armor
If any of the following hold, you will slip while trying to get on the steed, and will lose 10-14 hit points. This can also happen by chance when you're not impaired in any way.
To stop riding, do the #ride command again. When you dismount an unnamed steed, the game gives message "You've been through the dungeon on <steed> with no name.", or if you are hallucinating "It felt good to get out of the rain." Both lines are a reference to song A Horse With No Name.
Pros and cons
While riding, your carrying capacity will be set to maximum. Your steed will be more passive than when not ridden; it will not pick up items and will not spontaneously attack monsters. Instead, monsters have a chance of attacking your steed instead of you: when they do, then your steed will counterattack. You will move at the speed of your steed (a horse is as fast as a character wearing speed boots, and a warhorse is even faster). Polearms can be used effectively at close range while riding.
On the other hand, you cannot eat food (notably corpses) off the ground while riding (SLASH'EM removes this restriction, however), and can only pick items up if you have at least Basic riding skill. Pets are not reluctant to be ridden over cursed items. If you ride a non-flying steed downstairs while burdened, you will fall off and injure both legs. Also, you should not use Conflict while riding: your steed can throw you off. However, a ki-rin's high magic resistance and experience level will make it always resist (unless you level drain it below level 15).
Possible choices of steed
- Horse: grows stronger and faster, and is easy to tame, but is difficult to keep fed as it is herbivorous.
- Unicorn: does good damage and (like the warhorse) can have a speed of 32 when zapped by speed monster.
- Dragon: can fly, is carnivorous so easy to keep fed, and can be acquired by laying an egg, but is slow.
- Jabberwock: same advantages of a dragon (flies, good hit dice, good damage, carnivorous), has slightly better speed, but lacks the dragon intrinsics.
- Ki-rin: fast, can fly, can cast healing spells on itself, and does not eat (be aware that this means that it is more likely to go wild) but is difficult to tame and also somewhat rare.
- Centaur: slightly slower than warhorses and unicorns, but is omnivorous, and can equip a shield of reflection and a weapon.
- All quadrupeds: Leocrotta in particular due to its speed (18, same as ki-rin).
- In SLASH'EM there is Pegasus who is as fast as a warhorse, is stronger, can fly, and does not eat.
In general, all quCDJ can be ridden. Ki-rin and couatls are suited to be saddled and ridden as well. Foocubi are notable for giving a funny message if you attempt to saddle one ("Shame on you!"). Attempting to saddle a cockatrice or chickatrice without gloves is an instadeath, and neither monster can be ridden anyway.
Your steed will be subject to the traps that you ride through. This means that if you ride into a pit, your steed will be damaged by the fall. If you ride into a polymorph trap, your steed will polymorph (most likely into something that can't carry you). When you hit the ground, you will polymorph too. However, tameness is not decreased by riding into traps, even known traps, unlike other methods of leading a pet into a trap.
Your magic resistance will protect the steed as well. A polymorph trap will only make you feel "momentarily different" if ridden into while wearing a cloak of magic resistance. If you're worried about losing that powerful (and ridable) pet of yours to a random trap, riding might be just the thing for you. Note that amulets of unchanging will also prevent both you and your steed from polymorphing, but this obviously won't protect from other traps. Too bad you can't saddle an Archon.
It is possible to mount a steed if you are levitating "at will", as from quaffing a blessed potion of levitation, casting the levitation spell at skilled or expert, or invoking The Heart of Ahriman. ("steed's name magically floats up!"). Only invoking The Heart of Ahriman will levitate the steed along with you, however if you levitate via the potion or the spell while riding, you will find that you "cannot stay on" your steed, will have to remount if possible to levitate your steed.
You will move at the speed of your steed. If you have intrinsic or extrinsic speed you will not move any faster. If your steed is sped up or slowed (e.g., via wand), your movement will be affected. While movement is at the speed of your steed, many of your actions are done at your speed. Fighting, quaffing, reading, zapping, or engraving all rely on your speed instead of your steed's speed. It is thus still useful to wear speed boots even while riding.
Monsters will attack your steed. If you have a stethoscope, you can determine the health of your mount by using > as the direction to apply it. Be sure to run away if your steed is in trouble. You can also heal your steed with a spell of healing or extra healing by specifying > as the direction of the spell.
Spell-casting steeds can heal themselves even while you are riding them (ex. Ki-Rin).
Oddly, you cannot use stairs while your steed is eating, even though you can move around within a level.
The riding skill
Many classes have the riding skill. It takes 101 steps while riding to exercise the riding skill. To go from unskilled to basic, it will take 2020 steps while riding. Note that this may be fewer than 2020 turns since most ridable monsters are faster than the turn rate. For those 2020 steps, you won't be able to pick things up off the ground, which can be frustrating. However, there's a way around this: you can apply a bullwhip downward to snag items. There's a chance that the whip slips loose instead, or whips your steed into gallop (decreasing its tameness). Likewise, you don't have to dismount to tin a corpse.
Being unskilled at riding forbids you from picking things up from the floor. You also can't dip things in pools unless you're riding a swimming steed. Setting traps has a chance of failure, but the chance can be greatly minimized with good Luck, and you will be warned before taking the chance. Fumbling or using a cursed trap will increase the chance of failure. Failed beartraps will drop harmlessly to the floor, but failed land mines will explode.
Riding at lower skills while give you a penalty on your to-hit chance (-2 for unskilled, -1 for basic, and always an additional -2 when #twoweaponing).
Advancing beyond Basic is generally a waste of skill slots as the benefits are very minor. Though higher skill ranks improve rates of success for saddling, mounting, dismounting, and goading the steed to gallop, by the time you've exercised enough to qualify for the higher ranks you could already have achieved optimal success rates through improvement of the applicable stats, Dexterity and Charisma.
Each skill rank beyond Basic also gives +1 to most damage (and as Skilled also gives +1 to-hit, it's worth noting that advancing riding to Skilled gives the same benefits as advancing a weapon skill to Expert, at one-third the skill point cost!); sadly, this bonus does not apply to two-weapon combat, which is available to all roles who can advance riding to Skilled or higher.
In Slash'EM Extended there are much fewer restrictions on ridable pets. If the monster is tame, the player can apply a saddle and try to ride it; it doesn't matter if the monster is amorphous, whirly, unsolid, small/tiny or a form that can't normally be ridden. Many of them don't make good steeds. However, a pet with a high speed may actually be worthwile to ride (example: air elemental), especially if it's moving faster than a player on foot. Saddling a foocubus is possible too, but doing so will abuse the player's wisdom.