Pokémon Go fans are criticizing the recent launch of an elusive new creature that's now unavailable in many countries following a change by developer Niantic.

Last week, IGN reported that players were working together to track down Silicobra, the sand snake Pokémon, after its debut in Pokémon Go's latest "Sustainability Week" event. While spawns were rare, fans deduced a decent map of where the creature might appear based on US government geographical data — only for Niantic to change its criteria only hours after the map was more widely publicized.

IGN contacted Niantic for more information on why the change happened, but was told this question fell under Niantic's policy of not commenting on appearance rates for specific Pokémon, and redirected to the event's official blog post, which offers no further clues. A day later, however, Niantic did ultimately comment — although only after fans spotted further changes to Silicobra's availability once again.

"Trainers, we've adjusted Silicobra encounters to align more closely with its natural habitat," Niantic wrote on X/Twitter. "You can now find Silicobra slightly more frequently in desert-like areas."

It's a statement that doesn't really provide any further detail on what has changed or why — and more importantly, any further clues on where Silicobra can now be found. Players have reacted negatively to all of this, after initially the event was billed as a chance to encounter a Pokémon that was debuting in the game for the first time.

Now, the most recent fan-made map shows Silicobra as almost completely extinct in the Eastern US, almost all of Europe and Japan. If you live in the UK, your nearest Silicobra spawn point is likely Marseille, on the Mediterranean. That's after the creature was available in multiple UK cities upon its initial debut.

"It's disappointing that this was hyped as a new Pokémon release, and especially frustrating that it was originally released in more biomes and then rolled back," wrote mal138 in a lengthy thread on the changes to Silicobra's spawns on top Pokémon Go fan reddit TheSilphRoad. "But in general, I have no problem with a new regional, especially one that is available across the Midwest and west coast (from the map I saw recently)."

"I love a Pokémon I have to go look for," wrote Study_Realistic. "It means we can make a day of it, partner, kids, we get in the car and go adventure to find it, the feeling of achievement, doing something special, it makes for a good day. Harder and rarer to find the better. What breaks that is when the goalposts move.

"Wiglett I know I have to go to the beach to get. I go to the beach, I find Wiglett. Silicobra was advertised as the new mon and unless you were in the 0.1% right spot on a Tuesday, it wasn't available in the UK. That kills it. Instead of a sunny day out, you get a rug pull and an event you can't do."

"Transparency is the missing link in this biome update," wrote k6nch6n. "I don't mind rare spawns, but when Niantic 'fixes' things behind the scenes without a word, it turns exploration into a blind guessing game. People are making real-world efforts — visiting specific habitats based on community data — only to find out that the rules changed without notice."

While Niantic made no promise that the data set it initially used for Silicobra spawns would continue to be used long-term, the current lack of any in-game biome indicator means players only have the research undertaken by the game's community to go on.

Many have called for an in-game biome indicator to be added — so that areas marked as desert can actually be determined without needing third-party tools. This would move the Pokémon's ease of location closer to Wiglett, whose spawns typically correspond to areas where Pokémon encounters feature a beach background.

"There's absolutely zero transparency about biomes except the occasional background shift," Mix_Safe wrote, "but there doesn't seem to actually be a 'desert' biome background either."

Notably, Silicobra was not available through any other method, such as eggs, field research, or even the premium event pass.

Tom Phillips is IGN's News Editor. You can reach Tom at tom_phillips@ign.com or find him on Bluesky @tomphillipseg.bsky.social