View source for Challenges

'''Challenges''' are unique runs in the game. Isaac typically starts each challenge with one or more specific items which make normal play more difficult. With few exceptions, [[Treasure Room]]s are not available during challenges. Each challenge unlocks new content for the game, such as [[rune]]s when completed.

== General Strategy ==
Most challenges are designed to increase the difficulty of the game in a unique fashion. This doesn't mean all challenges are difficult, however; challenges like [[Computer Savvy]] are quite easy to beat. Some challenges do compensate for this by being especially punishing; [[Solar System]] is a good example of this. Each challenge has certain strategies that can be employed to make the run easier. However, there are a few strategies that can apply to all challenges.
* Challenges can be played in [[co-op]], allowing a second player to contribute to the run without being hindered in the same way Isaac is. This is especially useful in any challenge where Isaac is [[Blindfolded]], as the second player will be allowed to fire tears normally.
* Due to the lack of Treasure Rooms, [[Devil Room]]s become much more valuable. Some challenges can be made much easier by making just one deal, but it is worth noting that other challenges reduce Isaac's health to the extent that Devil Deals become too risky.
** Some rooms (including [[Crawl Space]]s) may have Treasure Room items by default. Since these items are random, results can vary from run to run.
** Because locked Treasure Rooms won't spawn, keys can be used far more liberally. Also, [[trinket]]s and [[item]]s that generate more coins, along with upgraded [[Shop]]s, can help Isaac acquire a greater range of powerful items.  
* {{i|The Bible}} instantly kills [[Mom]] and [[Mom's Heart]] / [[It Lives]]. All challenges require defeating Mom, and most require defeating Mom's Heart or It Lives, making this an extremely powerful item, especially in challenges where Mom or Mom's Heart / It Lives is the final boss.
** {{i|Pandora's Box}} will spawn The Bible if used in Womb II, Utero II, or {{dlc|a}} Scarred Womb II, making it a reliable way to acquire The Bible.
* [[Curse Room]]s can spawn items, making them valuable.
* {{dlc|na}} In some challenges, [[Dice Room]]s and the {{i|D4}} are very useful, allowing that challenge's starting items to be rerolled, thus removing most of the difficulty. NOTE: This changes depending on the challenge. Most challenge pages contain details on the results of rerolling.
** {{t|Butter!}} can also remove starter items.
* [[Blindfolded]] challenges are arguably the most difficult challenges due to Isaac's inability to fire tears. There are several methods to work around this.
** Familiars can provide an alternative method of dealing damage. Powerful familiars like {{i|Daddy Longlegs}}, {{i|Lil Brimstone}}, and {{i|Incubus}} are therefore highly useful items.
** {{i|The Boomerang}}, {{i|The Candle}}, and {{i|Red Candle}} are also useful for blindfolded challenges, since they recharge based on a timer, rather than an amount of cleared rooms.
** {{i|Clicker}} can allow Isaac to change into [[Lilith]], whose {{i|Incubus}} overrides the blindfolded effect by default.
** Some spacebar items like {{i|Tammy's Head}} can be really helpful, providing an alternative method of dealing damage.
* {{i|Chaos}} is a powerful item in challenges, as it can allow powerful items to be found more commonly, such as in the Shop or after defeating bosses.
* Defeating a boss beyond the specified end of the challenge (e.g. defeating [[Mom's Heart]] when the goal is to defeat [[Mom]]) will still spawn the trophy.
** {{dlc|a}} In some longer challenges (e.g. [[XXXXXXXXL]]), using a [[Sacrifice Room]] until it teleports Isaac to the [[Dark Room]] is a viable strategy. Once in the Dark Room, the trophy can be spawned by defeating [[The Lamb]].

== Notes ==
* Apart from the achievement related to beating the challenge, all achievements are locked. Also, no [[Donation Machine]]s will appear in any challenge.
* The challenge reward will not be unlocked unless the trophy is picked up. If a Devil Room or Angel Room appears allowing Isaac to go to [[Sheol]] or the [[Cathedral]], the unlock will be forfeited.
* [[Isaac]] will not start any challenge with {{i|The D6}}.

== Challenges List ==
{{table | challenge |
{{query | challenges }}
}}

{{nav|challenge}}