Again, it was quite a long time since the last major update (12.0, from 2021). Of course, the work never stopped -- improvements were continuously added to the game, so if you were following HyperRogue closely, you have seen these. For less active followers, here is a summary of the most interesting new stuff.

Dangerous to go in a line. Take a Crossbow!

Many roguelikes ensure their longevity by providing ways many different ways to play the game. This is done both by having many possible inventory-based builds (as reflected in HyperRogue's Orb Strategy Mode), but also by giving a choice of playing multiple kinds of characters, with different strengths and weaknesses; for example, the five different characters in Hydra Slayer, or 27 different species in Dungeon Crawl Stone Soup, further augmented by specialization and deity choices. However, this kind of specialization often relies on changing the damage produced by various kinds of attacks -- HyperRogue, with its focus on geometry and one-hit combat, was relatively lacking in this area. Could we still have something similar while still maintaining the focus on geometry?
HyperRogue 13.0 includes an option to play the game with another weapon: a crossbow instead of the classic blade! A classic traditional roguelike strategy is: when attacked by an overwhelming force of multiple enemies, move into a corridor, forcing them to attack one by one; HyperRogue combines this idea with hyperbolic geometry, making this strategy work even in open space, due to the geometry of the world itself. But why use your blade to attack them one by one, when you could also have a penetrating attack that kills the whole straight line of enemies in a single shot? As a counterbalance, the crossbow takes several turns to reload. Rethinking the concept of a straight line was fundamental for the development of non-Euclidean geometries; in HyperRogue, it becomes even more sophisticated, because this geometric concept needs to be interpreted in terms of grid tactics. Some roguelikes let you fire your ranged attack at any point, while in some, they work a bit like a Queen in chess: ranged attacks can be aimed only cardinally or diagonally. And in some, it depends on the type of ranged attack used. So, the crossbow could actually be a few different weapons. A crossbow which shoots only in "bull lines" is less universal than one that can shoot along any tile-based approximation of a hyperbolic straight line, but it takes less time to reload. There is also a third option, but we will just let you see for yourself.

New modes, geometries, and land structures

Of course, while the character in HyperRogue does not change that much, neither by player's customization nor by gaining in-world experience, HyperRogue focuses on changing the world itself, or the rules of the game. There is not much new in terms of whole new modes -- unless we count new options for the real-time multiplayer mode of HyperRogue, such as PvP or split screen or using dual focus projections -- but one of the things that can be changed is the geometry of the world... or, at least, the tiling.
Probably the most popular mathematical discovery of 2023 was the discovery of hat and Spectre tiles, which can tile the whole Euclidean plane by themselves, but only in non-periodic ways. Soon after this discovery, this tiling became available in HyperRogue.
While the rules of HyperRogue are specially designed for hyperbolic geometry, you can e.g. play the Minefield land in the Hat/Spectre tiling, to get a more original variation on Minesweeper. There are more options to customize the geometry of the world -- for example, the format to specify arbitrary periodic or some horocycle-based 2D tilings has been extended, three-dimensional geometries no longer include only regular hyperbolic and spherical honeycombs but their cells can be subdivided, and there is an option to play only on a finite portion of an infinite geometry. These are likely less balanced, but still cool for experimentation or visualization.
If you do not want to change the geometry of the world, you can still change how it is structured... New options shown in the images above replace the usual HyperRogue land structure (lands separated mostly by hyperbolic straight lines) with alternative ones. In one, every land is bounded by a horocycle (a shape existing only in non-Euclidean geometry that looks a bit like a circle but is actually infinite)...
In another, the hyperbolic plane is subdivided into lands like in a Voronoi tessellation -- some points are chosen as centers, every tile gets assigned to a land depending on which center is closest to it -- but where the centers are very rare... so rare that they are infinitely away.

Visualization

[previewyoutube=Rhjv_PazzZE;full][/previewyoutube] HyperRogue is not only about great roguelike gameplay, but also about non-Euclidean visualization! Since 2019, we could play in Thurston geometries; however, roguelikes were designed to be played in 2D, and most people find them less fun when you can move in three dimensions. Also since 2019 we could play the usual 2D game of HyperRogue, but view it in full 3D. However, this 3D view was restricted to use the 3D version of that 2D geometry: hyperbolic plane in three-dimensional hyperbolic space, sphere in three-dimensional spherical space, etc. Now, the HyperRogue engine features a large list of embeddings. Unfortunately, for the standard "hyperbolic soccerball tiling" that HyperRogue plays best in, only 3-dimensional hyperbolic space, and the "product space" where the third dimension is added in the Euclidean way, works. However, a sphere can be embedded in 3D Euclidean and hyperbolic geometry, and for the Euclidean plane, especially when wrapped in flat torus, there are lots of options -- including all Thurston geometries, and more! These are explored in this video. [previewyoutube=yqUv2JO2BCs;full][/previewyoutube] Another new thing is an option to create a world with portals between different geometries; we have shown this in this video with over 1M views, and the HyperRogue engine can be used to create spaces likes this, by placing bricks in different geometries like in Minecraft, connecting them with portals, and exploring them in VR. There is no real gameplay in these worlds, but hopefully we inspire other game developers to try new stuff!

Have fun!

On top of that, there was of course a large number of minor bugfixes and improvements. To get updates on HyperRogue and our other projects faster, join the HyperRogue discord server. Also wishlist RogueViz Collection for a collection of smaller non-Euclidean games. Have fun, and good luck!