R2

Sonic the Hedgehog CD

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It has been proposed that R2 be renamed and moved to Dubious Depths.
Reason for proposal: This appears to be the intended name for the zone according to the citations.

Dubious Depths

Scrapped round, Sonic the Hedgehog CD
Number of Acts: 3 (presumably)
Location: Little Planet
Level theme: underground/cave
Boss: R2 Boss

Dubious Depths^[1] (commonly known as simply R2 (Round 2) and previously known as Ridicule Root^[2] during development) is a scrapped Round from Sonic the Hedgehog CD. Set to take place between Palmtree Panic (Round 1) and Collision Chaos (Round 3), it was removed at an early stage of development. Hints to its existence can be found in the Mega-CD and Windows PC versions of the game.

It is thought to be analogous to Marble Zone in the original Sonic the Hedgehog, with leaked concept art suggesting a stage that took place at least partially underground. Geographically, it would be located on the Little Planet.

Design

Little Planet concept, complete with a "2R" design.

For many years, the existence of the round was little more than speculation, gathered from inconsistencies in the game's files. Proof of its existence came in a Sonic CD developer's diary video, uploaded by Sega Europe onto YouTube on November 29, 2011 (to promote the 2011 re-releases of the game)^[3]. In the video, a sketch of what appears to be rainbow-coloured waterfalls appears, something confirmed by 2011 port's lead developer, Christian Whitehead as concept art for the zone^[4].

With the release of Sonic Origins in 2022, further concept art was released, with mentioned of an "2R" level on a map of Little Planet, with the level order again suggesting the round was located between (what looks like) Palmtree Panic and Collision Chaos. The art shows a forest of trees and what appear to be iron beams or totems, and an underground section with traps and obstacles such as fans that would have possibly lifted Sonic in the air. Mountains can be seen further behind.

Enemies

Three normal enemies and one boss are known to belong to the round, according to Whitehead. This includes an antlion enemy, a worm or snake, and a enemy armed with a drill. Concept art depicting Eggman in a wheel mech may indicate plans for the boss.

Worm/Snake (CDS probably stands for "CD Sonic", an early name for Sonic CD)
Drill armed enemy
Wheel boss concept

Unfinished sprites also shared by Whitehead^[5] show how these enemies may have appeared in game. This time, Eggman is depicted riding a vehicle with a giant wheel on the bottom and a spring on the back.

After the round was removed, the Antlion enemy was considered for Metallic Madness (R8) before being scrapped entirely (the sprite was slightly redrawn, with the highlight on it being smaller). It is speculated that parts of Metallic Madness' level design, namely the sloped pits, may have been created with the Antlion enemy in mind, before being repurposed. The leaked prototypes suggest the developers experimented with these sections before deciding on regular, upwards spikes.

Removal

Several explanations have been given for the round's removal. Naoto Ohshima has suggested it may have been down to the design being incompatible with Sonic's speed^[1], while Masato Nishimura believes the decision was made because the music data did not fit into the CD-ROM of the game^[6].

In an interview with Jim Tretheway regarding the PC version of the game, it was stated that the level was likely cut as it didn't meet quality standards^[7].

Final game leftovers

The level select screen in the 510 prototype shows every level in the game on one screen.

Questions about the round were raised shortly after Sonic CD's release. Performing its level select code, the level order does not include any levels beginning with a "2", leading to speculation that the second level no longer existed on the disc. This pattern was later mirrored by the PC version, which in the game's files, has folders for "R1" and "R3", but not "R2".

Perhaps the biggest clue that something is missing from the game is the ending sequence, which shows animated sections of the game, in level order. After a sequence in Palmtree Panic, Sonic is seen what looks like a ruined area with blue or grey metallic structures or pillars, with areas of vegetation growing around. Stone tiles collapse as Sonic touches them, revealing quicksand, and at the end, Sonic is attacked by the unseen Antlion enemy. Nothing resembling this sequence exists in the final game.

(an animated gif of the scene can be found here.)

These animated sequences were created in advance of much of the game, and are therefore thought to be based on older concept art and ideas, including those of the scrapped round. This sequence was left in the final game (adjusted for the Mega-CD's limited colour palette) and subsequent re-releases, as well as the video included in the Sega Saturn compilation, Sonic Jam.

According to Masato Nishimura, the default song in the D.A. Garden mode, "Little Planet" (composed by Masafumi Ogata), is a leftover from the round^[8]. A brief remix of the "Bad Future" theme of the stage is also present in Ogata's song "Techno Power Mix", composed for the 1994 album Sonic the Hedgehog - Remix. "Sonic Stream", another of Ogata's tracks from the same album, is also speculated to feature pieces, or be a full remix of the round's "Good Future" theme.