Slay the Spire 2 developer Mega Crit has offered a detailed look into the creation of Aeonglass, the game's recently implemented Act 3 boss. This boss replaced the previous iteration, Doormaker, as part of ongoing efforts to refine the roguelike deckbuilder's gameplay and challenge. Aeonglass, with its hourglass-inspired design, is noted as one of the game's most visually striking characters.
In a Steam blog post, Mega Crit animator Chris Gortz elaborated on the design journey. Early concepts for a replacement boss included ideas such as a "multi-faceted pillar of death" that could shift its sections to reveal different abilities, evolving Doormaker's original rocky portal aesthetic. However, the team ultimately decided to move away from these concepts in favor of the hourglass theme.
The development team explored several variations on the killer hourglass concept, with one particular design ultimately being chosen after internal discussion. Gortz shared that initial tests involved simulating 3D rotating metal rings in a 2D space, which, while visually unrefined, served as a crucial proof of concept. To develop Aeonglass' combat mechanics, initial sketches helped solidify the idea of a "big atom" capable of blast and slice attacks.
Art director Marlowe Dobbe suggested that the material within the hourglass should behave more like "lava lamp goo" than traditional sand. This artistic direction led Gortz to utilize the same smoke shader previously employed for the Living Smog boss, contributing to Aeonglass' distinctive visual effect.
Aeonglass has already undergone adjustments in recent beta patches, including nerfs to its front-loaded damage and swapped animations. Further modifications are anticipated as the developer continues to iterate on the Act 3 boss. Slay the Spire 2 is currently in early access and is not expected to reach its 1.0 launch until 2027 at the earliest, following a development cycle similar to its predecessor. Console versions have not yet been confirmed but are anticipated around the time of the full release.