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Hydra Slayer

Current version: 18.0 (Nov 12, 2016) - download or buy

You are facing a nine-headed hydra. Your flaming longsword cuts five heads in each swipe (no more, no less), which will kill a five-headed hydra, but a larger hydra will regrow two heads after each swipe. Your storm scythe cuts exactly seven heads, but it makes ten heads grow back if the hydra is not dead. Is it possible to kill the hydra? What if you also had a silver dagger, which cuts just one head, but makes five heads grow back? (Solution)

Hydra Slayer is a Roguelike game focused on one thing: slaying Hydras. It is inspired by Greek mythology, Dungeon Crawl, MathRL seven day roguelike, and some mathematical puzzles about brave heroes slaying many headed beasts.

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OK, it's probably not number theory, but it is awesome. Thanks for releasing the source (so I can run it on Linux). I'm on my third game, the first game consisting of me dying before I could properly see what I was doing.
- CGGreatHouse, MyMathForums

Also you know you're playing a funny game when you make your opponent stronger so he's easier to kill.
- BDR, Attnam IRC channel

Difficult, but worth it. Great game! Very unique and interesting mechanics. Definitely not for the faint of heart (or mind).
- William Graber, review on Google Play

Hydra slaying has a long history.

First explorers who have met hydras were completely unable to do any harm. As they cut hydras' heads, two new heads always grew in place of each one cut.

Some of them started using clubs instead of swords. However, this was only a temporary solution. A club may stun a hydra, and make it temporarily less dangerous, but not kill it. When time comes, it will wake up and attack further. Hydras remained indestructible monsters.

Some mages have been employed to research methods of slaying Hydras. The first thing they have invented were Runes of Decapitation, which could kill a completely stunned hydra, or permanently destroy some heads of a non-completely stunned one. Another thing were Runes of Cancellation, which could remove hydra's regenerative abilities. However, both of these Runes were one-use items and very expensive to create, and thus not practical.

Then, a report came, claiming that heads won't regrow if the sword was put on fire. Apparently all Hydras in some region were killed using that method. Their meat was found extremely tasty, their blood good for healing wounds (due to hydras' natural regenerative abilities), and their scales good for improving armors.

Mages tried this method. Unfortunately, it did not work for them, though. However, they have experimented with other kinds of magically imbued weapons. It turned out that some enchantments will reduce the number of heads regrown. Possibly even no heads will regrow. Some hydras could be slayed after these findings, but not all. It is rumored that some mage long ago created a weapon which could slay any Hydra without regrowing heads, but he got overconfident and killed, and the secret was lost.

Mages experimented with their magical weapons even further. And they had a new result: weapons which could cut (or stun) several heads at once. If they cut all heads, the hydra was killed. If not, the Hydra would usually regrow the same number of heads as if only one head was cut. The mages were happy with that major result.

Of course, some new hydra slaying weapons and magics were created later, but they were nothing compared to the previous major achievement. The numbers of Hydras kept decreasing, and finally, they disappeared, and were almost forgotten... And less and less people became acquainted with the hydra slaying techniques, as other people laughed at them, because their profession was completely useless in these times.

Now you, a young student, have heard about a manifestation of hydras in so called Hydras Nest. Apparently some brave knights came to kill the Hydras... Brave, but stupid. Even if they equipped themselves with mighty hydra slaying weapons, they had no knowledge about how to use them correctly. What use is a mighty sword which can cut ten heads in one swipe, against a Hydra which has only 9 heads? All these knights have been killed.

You are more clever. Since your earliest years you have had an unnatural ability to count people in an instant, and your great grandfather has suggested you to pursue the Hydra Slayer career, and learn the forgotten art of Hydra Slaying. Now, you will show people that it is not just an useless funny thing. You take two small magical weapons and some magical items, hoping to rob better ones off dead bodies of these stupid knights, and head to Hydras Nest. Of course, not that you are one of these clever guys who are too scared and weak to be useful in a battle... you could also wield a two handed weapon with one hand.

The game counts various statistics about your character. I think the game is quite challenging, but not enough to require you to use up all your resources, so after winning once, you can try to win again with using less items, or taking less wounds, or using different strategies.

The game has two victory conditions (called "winning a battle" and "winning a war"). After obtaining the first one, you can try the second one (which should be winnable even without using one of the Potions of Life). You can try optimizing your play in both games. After winning the war, you can still go down, although the enemies get tougher and you gain less and less health, and items are not sufficient, so you will eventually have to stop.
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Thanks to Slashie for hosting this at RogueTemple!
@ Zeno Rogue Games @ Vapors of Insanity @ Necklace of the Eye @ [ Hydra Slayer ] @ HyperRogue @ Untahris @
@ [ About ] @ Solution to the puzzle @ Features @ Downloads & Credits @ Screenshots @ History @ Beginner's Guide @ Spoilers @ Android @