Save Files

This is Dead Cells' specific binary save file format. It stores multiple serialised objects in a compressed format along with hashes to prevent corruption or tampering.

note

All this information was obtained from f@34927 static tool.$Save.genSave (User, Bool) -> haxe.io.Bytes - if you'd like to help out, try looking at this function yourself!

warning

This is not complete! Although a partial reimplementation of hxbit is available in hxbit.py, this can only read - not write - save file data.

A working example of reading and writing a Dead Cells save file is available in alivecells as savetool.py.

Format

File

Size (bytes)	Name	Struct
59	Header	Header
Variable	Payload	Payload

Header (PC version)

Size (bytes)	Name	Description	Struct
4	Magic	0xDEADCE11	None
1	Version	Current format version, usually 1	Unsigned 8-bit integer
20	Checksum	SHA-1 raw hex digest of the file's contents, assuming these 20 bytes are 0x0 while taking the hash	None
20	Git hash	Current long commit hash of the game, as a hex digest	None
10	Build date	Build date of the game version creating this save file	UTF-8 string
4	Flags	Flags and metadata about the save file - mostly unknown	Flags

Header (mobile version)

Size (bytes)	Name	Description	Struct
4	Magic	0x20DEAD19	None
1	Version	Current format version, usually 2	Unsigned 8-bit integer
20	Checksum	SHA-1 raw hex digest of the file's contents, assuming these 20 bytes are 0x0 while taking the hash	None
20	Git hash	A value for each major version of the game, currently 0000DEADCE110000000000000000000300500000	None
10	Build date	Build date of the game version creating this save file	UTF-8 string
4	Flags	Flags and metadata about the save file - mostly unknown	Flags

Flags

Bit	Value (Dec)	Value (Hex)	Name	Type	Description
0	1	0x1	S_User	Data Chunk	If set, a chunk containing persistent user progress (unlocks, cells, gold) exists.
1	2	0x2	S_Game	Data Chunk	If set, a chunk containing an in-progress run exists. If clear, the save was made from the main menu.
2	4	0x4	S_UserAndGameData	Data Chunk	If set, a chunk containing general game metadata exists.
3	8	0x8	S_Date	Data Chunk	If set, a chunk containing the 8-byte save timestamp exists.
4	16	0x10	S_Experimental	Feature Flag	If set, the save was made while the game's experimental/beta features were enabled.
5	32	0x20	S_UsesMods	Feature Flag	If set, the save was made with mods active. This is determined by checking if user.activeMods is populated.
6	64	0x40	S_HaveLore	Feature Flag	If set, indicates the save supports lore rooms. This flag is unconditionally set on all modern saves.
7	128	0x80	S_VersionNumber	Data Chunk	If set, a chunk containing the 4-byte float game version exists.
8	256	0x100	S_DLCMask	Data Chunk	If set, a chunk containing the 4-byte integer bitmask of installed DLCs exists.
9-31	-	-	Unused	-	These bits are currently unused but reserved for future expansion (which is unlikely). They are always 0.

Payload

The payload is a Zlib-compressed blob that contains the actual save file - some of them are hxbit serialised data, and others are just raw bits and pieces. They follow the order of the data chunk flags that were set previously - basically, if a data chunk flag was 1, then the chunk is present in the save file. The payload is compressed with Zlib level 9 (maximum) compression. To manipulate it, read it as follows:

• Decompress the payload (it has headers, so any stock zlib implementation can handle it)
• Figure out how many data chunks are enabled
• For each of those data chunks that's enabled, read a Chunk from the payload blob, seeking forward in it as you do.

Chunk

Size (bytes)	Name	Description	Struct
4	Size	Size of the contents	Unsigned 32-bit integer
Variable	Contents	Raw bytes of the save file chunk contents	Varies, see Chunk Formats

Chunk Formats

Depending on what kind of data chunk you're reading, the format of its chunk in the save file changes. Here's a basic map:

Bit	Name	Type
0	S_User	hxbit Data
1	S_Game	hxbit Data
2	S_UserAndGameData	hxbit Data
3	S_Date	Date Chunk
7	S_VersionNumber	VersionNumber Chunk

Date Chunk

Size (bytes)	Name	Description	Struct
8	Date	Date of save file creation as a unix timestamp	Double

VersionNumber Chunk

Size (bytes)	Name	Description	Struct
4	Version	Major game version for this save file, eg 34 or 35	32-bit float

hxbit Data

This data is serialised with help from hxbit - a Haxe library that enables serialisation of arbitrary objects to binary representations. This format has been partially reversed in hxbit.py.

See the full page for format specs.

Additional notes about saves from the mobile version

The chunks S_Game and S_UserAndGameData cannot be copied from a PC save to a mobile save, because mobile has no implementation of the Twitch integration features; those Twitch features are always referenced in those two chunks on a PC save even when they have not been activated, leading to a crash when trying to pass them on the mobile version.

However, the S_User chunk, which contains the meta progress of the save (including unlocked items), can be passed from a PC save to a mobile save.