Animation delay, commonly referred to by its two main subtypes, splash delay and explosion delay, is a game rule in Lynx and Chip's Challenge 2 that causes a splash in water or an explosion from a bomb to temporarily be an acting wall to the player (monsters and blocks will erase them if they otherwise can, and attempt to, enter the tile).
In typical cases, i.e. pushing a block into water or a bomb and then waiting to step on that tile, the first frame of animation happens as soon as the block finishes entering the tile, which is 1 tick before the player can start pushing against it. For clarity, since the amount of waiting can change based on circumstances, "animation delay" will always refer to the animation's duration in this article.
In CC2, animation delay always lasts for 6 ticks, or 1.5 moves. In Lynx, animation delay can last for either 11 or 12 ticks (2.75 or 3 moves). The length of the delay is actually dependent on the current step parity; if the animation begins on an even, even+2, odd, or odd+2 tick (e.g. the player starts a level in even step and pushes a block into water on the first move), the delay will last 12 ticks; otherwise (e.g. the player cleared the resulting dirt as soon as possible and pushes a second block into water immediately after), the delay will last 11 ticks.
Animation delay does not exist in MS. This is often seen as one of its strengths, as animation delay is usually more of a hindrance than a help, especially in long block-pushing levels such as On the Rocks. One particularly interesting example of explosion delay can be seen in the level Sealed Doors in the Spacecraft, which features a Lynx-only bust involving a partial post using an explosion from a bomb. Combined with block slapping, animation delay is one of the things that makes optimization in Lynx and CC2 such a challenge, sometimes even more so than MS.