Look on the bright side: there is no way any new Conan game
could be as bad as Conan: The Mysteries of Time. No way whatsoever.
Sure, a good Conan game needs good combat, but that isn't to say that's all there is to it. The Conan stories have a lot of appeal beyond hacking dudes to pieces: there are Conan's gigantic melancholies and gigantic mirths, the exploration of the Hyborian Age, battle tactics and strategy, Hyborian lore and legend, uncovering mysteries, and plain old fashioned girls & grog. Therefore, in addition to the combat/stealth which should make up the bulk of Conan gameplay experience, I suggest the following facets of gameplay.
In addition to, you know, adapting the bloody stories in some manner.
An Age Undreamed Of
A whole world rich in history, culture, folklore and myth - exploit it!
Conan displays a growing knowledge of history over the course of the stories, and it serves him well. He can use his knowledge for many purposes: gaining more approval from the scholarly and noble community; impressing suspicious locals with his affinity for the area; appraising items for more/less money; all of which leads to new lines of dialogue to open up new adventure opportunities. It can also allow Conan extra help when an adventure could benefit with familiarity with Hyborian history.
Conan also encounters many ancient relics, sigils, tomes, artifacts and wonders over the course of his adventures, and they often save his very life. Each piece of knowledge he discovers aids him in myriad ways: a secret sign that allows him access to sealed tombs, a valuable trinket, a missing relic that scholars would pay handsomely for, a powerful amulet. This could be in the form of puzzles in ancient ruins, deciphering runes with knowledge gained from reading dusty old tomes or from scholars, to plain old-fashioned site exploring. The Hyborian Age isn't the sort of place you can get some measly +1 Amulet of Protection at any village vendor: such powerful magical items are only found through great effort and exploration.
Naked Deserts and Sunless Jungles
Even ignoring the scorpions, spiders, snakes, centipedes, jackals,
vultures, kites, thorns, cacti, the desert heat should be a danger in itself.
The more Conan knows about the local environment, flora and fauna, the more effective he is at surviving. If he knows that a certain type of fruit is edible, he will be able to use it to heal: if he knows the hunting patterns of a particular beast, he's more effective at killing it; if he knows the lay of the land, he's more likely to avoid its traps and pitfalls.
If Conan encounters a leopard for the first time, he could dispatch it like he could any beast. However, if he learned of leopards and their attack patterns from scholars, books, soldiers or other sources, he would have an advantage, and would be able to kill them quicker, in addition to knowing that their pelt is highly prized to certain traders. Prior knowledge also provides the player with hints like its endurance, strength and speed, what sort of attacks it makes, and other useful snippets. This can be crucial in deciding which snakes are venomous, whether an animal is wounded or berserk (and thus more dangerous), if an animal is protecting its young or is young itself. If Conan comes across an animal he's never seen, he can find out more by going to a local scholar: if even they don't know what it is...
Similarly, if he comes across an Apple of Derketa without prior knowledge of them, he would have no way of knowing if it was safe to eat or not, though there might be clues nearby like dead animals and the stains of its purple poison: however, if he had prior knowledge, he would instantly identify it as such. He could then lather his sword in its juices, making it even more deadly, and remember not to eat it. Without that knowledge, the player could always try a bite and hope for the best, though that would naturally not be a great idea at the best of times. Prior knowledge is crucial when it comes to Black Lotus: if Conan knows about it, then the game's heads-up display would immediately warn of its proximity, and Conan could give it a wide berth. If he doesn't, however, then the player stands the chance of blundering right into a grove of the flowers and succombing to a deathly coma.
Environment is as deadly as plants and animals if Conan isn't careful: sinkholes, quicksand, tar pits, petroleum seeps, Mazukus, If I'm feeling cruel, I might introduce a "hardcore mode" a la Fallout: New Vegas, where Conan has to eat, drink and sleep periodically, healing takes time, injuries are potentially fatal, and overexposure to the elements could result in dehydration/hypothermia/hyperthermia without proper protection.
Questions of Reality and Illusion
Test your philosophical mettle!
Conan discusses theology, religion, philosophy, existentialism, politics and ethics on more than a few occassions. Again, this would open up similar opportunities as history: adventures, dialogue options, comments, maybe even stat boosts. Conan could talk to anyone, from a wandering Nemedian skeptic to a Zamorian philosopher visiting a Pelishti Wise Man. For example, Conan encounters a scholar in a tavern. If he's gathered enough philosophical acumen to debate with him, said scholar may hire Conan for a job - perhaps bodyguard duty as he goes to visit a fellow intellectual, send him to investigate a local archaeological site, assassinating a rival, things like that.
Not only scholars would be impressed, but a variety of characters - nobles, soldiers, royalty, serfs, slaves alike, all can be moved or convinced by a little philosophical guile. Best of all, knowing different philosophies and takes on life gives a slight edge in tactics. If you know about a group's faith, you can use it against them: taunt the Shemite's fatalism, the Nordheimr's Valhalla, and so forth. Mocking an enemy using their own beliefs adds a little extra spice, and could make them act rashly - playing right into Conan's hands. Conan's remark to Heimdul ("not in Vanaheim, but in Valhalla will you tell your brothers that you met Conan of Cimmeria!") is a bit more of personal than "I'll vanish your head from your shoulders!"
Oh, and if - if - I was going to have a nod to Milius' Genghis Khan motif, Conan would not say it: it would be some nameless drunk Hyrkanian or Turanian soldier, moments before throwing up. I probably wouldn't, though: it's better to just ignore the films than to ridicule them and alienate the Conan the Barbarian fans. Besides, it would just come across as sour grapes.
Flagons & Jacks
This is my second favourite Vallejo Conan painting:
the other's that one he did for Savage Sword with Conan on the cross.
Conan's gigantic melancholies include a love of the drink. Conan's tipple of choice appears to be wine, though he's certainly not averse to ale or other beverages, and for food he loves nothing more than a great big joint of beef. I think whenever Conan's in a tavern, a ship's hold, or similar venue, he should turn the place into a roaring event. I'd suggest drinking songs, where Conan leads the bar in a rousing sea shanty or soldier's marching rhyme: doing so will increase his standing in the town among the common folk, as well as increase camaraderie with his companions. When Conan's a captain, his men will fight longer and harder if he joins them in festivities.
That isn't to say it should all be cheerful: drinking too much would affect your balance, combat prowess, sense of direction and energy levels. You could go careening into a wall and knock yourself out if you aren't careful. Conan could also initiate tavern brawls. The Witcher had a delightful "bar fight" mechanic that I think would work excellently for Conan, too, and that could be expanded into a bar-wide scuffle. Doing this when the guards come around to arrest Conan for his thieving/slaying/whatnot could offer him a chance to escape into the night.
Butter on a Hot Skillet
Yeah, I hate this image, but it serves a purpose here.
I don't want to overplay the whole Gore, Girls and Grog thing, but it's a part of Conan all the same, and should be included. Ideally, there should be a number of ways to approach women: brusque proposition, coy flirtation, even romantic tenderness, using Conan's strength, physique, intellect, personality and guile to differing effect. Not all girls go for the same thing, after all. (WARNING: don't click any of the links in the following paragraph if you're in a work environment!) I'd prefer not to use the puerile God of War/Hot Coffee sex game if I can help it, nor the melodramatic soap opera silliness of Mass Effect or Dragon Age: my model for good sex in videogames would be Heavy Rain (sans piano.) Thus if one wishes, they can make Conan a violent and powerful lover, or a surprisingly gentle and considerate one. Conan displays both sides as king (passionate and reckless to Zenobia in The Hour of the Dragon, but apparently gentle to his concubines in "The Scarlet Citadel"), so I'd guess Conan just instinctively knows what kind of lovemaking an individual woman is most receptive to.
Example: Conan approaches a tavern wench. (a: "You, wench, come to my chamber." b: "By Crom, you're a comely lass - I'll make you Queen of the Blue Sea and light the capital of Turan to light your way to my tent!" c: "Far have I wandered, girl, but the likes of you I've never seen!" d: say nothing, just stare lustfully, etc). If successful, the girl accompanies Conan to his chamber. (a: rip off her clothes. b: throw her to the bed. c: grab her and smother her with kisses. d: take her hand and gently lead her to the bed, etc) And so on, with different options to be rough or gentle, romantic or uncouth. Obviously different approaches work whether a woman is a barmaid, noble, slave, warrior-woman or queen, but even within those archetypes differences abound. Sometimes you might have to do something for her, others you may need to prove you're worthy of her, and on occassion, you might just have to (gasp) get to know her!
The situation one meets the woman also impacts on Conan's relationship with her. Romanceable women may include poor slave girls trapped in some godforsaken ruin that you have to rescue, warrior women you fight alongside, noblewomen you accompany through hostile territory, queens you're working for, or just someone you find in a tavern. (An aside: remember the chained-up maidens in 2007's Conan? That was a real missed opportunity to have some fun. I would have it so there were different benefits to unchaining the women: rescuing a slave gives Conana boost in attack/speed/strength from his instinctive desire to protect her; a warrior woman helps Conan in the fighting; a princess or noble gives monetary rewards on safely getting her back to her people, and so forth.)
All I ask is that if you're going to include sexuality in Conan, at least give the option to make it something more meaningful and adult than Puerile Adolescent Wish Fulfilment.
Sword-play on a Larger Scale
Like this. Times ten.
Conan's been a soldier and general in enough stories to plan battle actions on a substantial scale, and this needs to be reflected in a Conan game in some way. For inspiration, something like Bladestorm: The Hundred Years War (without the awful glowy effects or sound) or Viking: Battle for Asgard might work, with Conan accompanied by a battalion of soldiers under his command. He can give limited orders: hold ground, move defensively, charge, change formation, and whatnot. This would work for any situations where he's a bandit leader, pirate captain or hetman, as well as a captain of the spearmen/swordsmen/horsemen in a larger army. Obviously pirates are going to be less disciplined than mercenary spearmen, so options for orders are limited depending on Conan's force. Ship battles would mostly function in the same way as land battles, except prior to engagement, Conan's ship would ram into the enemy, or snare it with grappling hooks. Position and elevation would be key, with high ground and flanking offering significant advantages.
For when he's a general or king, he would be accompanied by a second-in-command figure, to whom he would dictate larger field actions (ie "order the cavalry to flank the left side," "order the cavalry to flank the right," "order the cavalry to charge head-on," "have the cavalry feint a charge to draw the enemy out of formation" etc), and see this happening around him. Thus, while Conan could dominate on an individual level, he has to use tactical acumen to win the battle.
The Road of Kings
It turns out strangling and usurping was the easy part.
Fable III flirted with the idea of running a kingdom, but sadly it ended up something of a disappointment, with only a dozen or so big decisions to make, and little after. I think the idea's too good to give it a miss. Let Conan make decisions that affect the kingdom: war policies, economic decisions, cultural growth, social reforms, whatnot. Let him visit other kings, lead his armies to glory, pick his concubines, take diplomatic trips to parts of the world previously inaccessible to him.
However, that sense of the throne being a "gilded prison" shouldn't be forgotten. Becoming king is a huge responsibility, and Conan's freedom is severely restricted. He can't just go hobnobbing with corsairs or saunter dark alleys anymore: he needs disguises, plans of action, and more. What's more, he has to deal with assassinations, revolts, disease, disaster, invasion, coups, and enemies his sword cannot touch. It opens up to a different sort of challenge - though if the player wants, they can just wait until an opportunity to stretch their muscles comes along.
There are more things to consider: what sort of weapons should be in the game, the level set up, sandbox vs linearity, characters, combat style, what stories should be adapted and how. There are so many ways of approaching a Conan game, it's amazing there aren't more of them.
Here's hoping the new game's a success, and leads to a renaissance of Conan games.