diff --git a/src/scripts/bgi/archive/bse.rs b/src/scripts/bgi/archive/bse.rs
new file mode 100644
index 0000000..11bdd51
--- /dev/null
+++ b/src/scripts/bgi/archive/bse.rs
@@ -0,0 +1,165 @@
+use crate::ext::io::*;
+use crate::scripts::base::*;
+use crate::types::*;
+use anyhow::Result;
+use std::io::{Read, Seek};
+
+pub trait BseGenerator {
+    fn next_key(&mut self) -> u32;
+}
+
+fn rtor(v: u32, count: u8) -> u32 {
+    let count = count & 0x1F;
+    return v >> count | v << (32 - count);
+}
+
+fn rot_byte_r(v: u8, count: u8) -> u8 {
+    let count = count & 0x07;
+    return v >> count | v << (8 - count);
+}
+
+fn rot_byte_l(v: u8, count: u8) -> u8 {
+    let count = count & 0x07;
+    return v << count | v >> (8 - count);
+}
+
+pub struct BseGenerator100 {
+    key: u32,
+}
+
+impl BseGenerator100 {
+    pub fn new(key: u32) -> Self {
+        BseGenerator100 { key }
+    }
+}
+
+impl BseGenerator for BseGenerator100 {
+    fn next_key(&mut self) -> u32 {
+        let key = self
+            .key
+            .overflowing_mul(257)
+            .0
+            .overflowing_shr(8)
+            .0
+            .overflowing_add(self.key.overflowing_mul(97).0)
+            .0
+            .overflowing_add(23)
+            .0
+            ^ 0xA6CD9B75;
+        self.key = rtor(key, 16);
+        self.key
+    }
+}
+
+pub struct BseGenerator101 {
+    key: u32,
+}
+
+impl BseGenerator101 {
+    pub fn new(key: u32) -> Self {
+        BseGenerator101 { key }
+    }
+}
+
+impl BseGenerator for BseGenerator101 {
+    fn next_key(&mut self) -> u32 {
+        let key = self
+            .key
+            .overflowing_mul(127)
+            .0
+            .overflowing_shr(7)
+            .0
+            .overflowing_add(self.key.overflowing_mul(83).0)
+            .0
+            .overflowing_add(53)
+            .0
+            ^ 0xB97A7E5C;
+        self.key = rtor(key, 16);
+        self.key
+    }
+}
+
+pub struct BseReader<T: Read + Seek, F: Fn(&[u8], usize, &str) -> Option<&'static ScriptType>> {
+    reader: T,
+    header: [u8; 0x40],
+    detect: F,
+    pos: u64,
+    filename: String,
+}
+
+impl<T: Read + Seek, F: Fn(&[u8], usize, &str) -> Option<&'static ScriptType>> BseReader<T, F> {
+    pub fn new(mut reader: T, detect: F, filename: &str) -> Result<Self> {
+        let version = reader.peek_u16_at(0x8)?;
+        if version != 0x0100 && version != 0x0101 {
+            return Err(anyhow::anyhow!("Unsupported BSE version: {}", version));
+        }
+        let _checksum = reader.peek_u16_at(0xA)?;
+        let key: u32 = reader.peek_u32_at(0xC)?;
+        let mut header = [0u8; 0x40];
+        reader.peek_extract_at(0x10, &mut header)?;
+        let generator: Box<dyn BseGenerator> = if version == 0x0100 {
+            Box::new(BseGenerator100::new(key))
+        } else {
+            Box::new(BseGenerator101::new(key))
+        };
+        Self::decode_header(&mut header, generator)?;
+        Ok(BseReader {
+            reader,
+            header,
+            detect,
+            pos: 0,
+            filename: filename.to_string(),
+        })
+    }
+
+    fn decode_header(data: &mut [u8; 0x40], mut generator: Box<dyn BseGenerator>) -> Result<()> {
+        let mut decoded = [false; 0x40];
+        for _ in 0..0x40 {
+            let mut dst = generator.next_key() as usize & 0x3F;
+            while decoded[dst] {
+                dst = (dst + 1) & 0x3F;
+            }
+            let shift = (generator.next_key() & 7) as u8;
+            let right_shift = generator.next_key() & 1 == 0;
+            let symbol = data[dst].overflowing_sub(generator.next_key() as u8).0;
+            data[dst] = if right_shift {
+                rot_byte_r(symbol, shift)
+            } else {
+                rot_byte_l(symbol, shift)
+            };
+            decoded[dst] = true;
+        }
+        Ok(())
+    }
+}
+
+impl<T: Read + Seek, F: Fn(&[u8], usize, &str) -> Option<&'static ScriptType>> Read
+    for BseReader<T, F>
+{
+    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
+        if self.pos < 0x40 {
+            let bytes_to_read = 0x40 - self.pos;
+            buf[..bytes_to_read as usize].copy_from_slice(&self.header[self.pos as usize..]);
+            self.pos += bytes_to_read;
+            Ok(bytes_to_read as usize)
+        } else {
+            let true_pos = self.pos + 0x10;
+            self.reader.seek(std::io::SeekFrom::Start(true_pos))?;
+            let bytes_read = self.reader.read(buf)?;
+            self.pos += bytes_read as u64;
+            Ok(bytes_read)
+        }
+    }
+}
+
+impl<T: Read + Seek, F: Fn(&[u8], usize, &str) -> Option<&'static ScriptType>> ArchiveContent
+    for BseReader<T, F>
+{
+    fn name(&self) -> &str {
+        &self.filename
+    }
+
+    fn script_type(&self) -> Option<&ScriptType> {
+        (self.detect)(&self.header, self.header.len(), &self.filename)
+    }
+}
diff --git a/src/scripts/bgi/archive/mod.rs b/src/scripts/bgi/archive/mod.rs
index 59a6efe..3346cbb 100644
--- a/src/scripts/bgi/archive/mod.rs
+++ b/src/scripts/bgi/archive/mod.rs
@@ -1,3 +1,4 @@
+mod bse;
 mod dsc;
 pub mod v1;
 pub mod v2;
diff --git a/src/scripts/bgi/archive/v2.rs b/src/scripts/bgi/archive/v2.rs
index 7d2daf2..5c61fe2 100644
--- a/src/scripts/bgi/archive/v2.rs
+++ b/src/scripts/bgi/archive/v2.rs
@@ -1,3 +1,4 @@
+use super::bse::*;
 use super::dsc::*;
 use crate::ext::io::*;
 use crate::scripts::base::*;
@@ -6,7 +7,7 @@ use crate::utils::encoding::encode_string;
 use crate::utils::struct_pack::*;
 use anyhow::Result;
 use msg_tool_macro::*;
-use std::io::{Read, Seek, Write};
+use std::io::{Read, Seek, SeekFrom, Write};
 use std::sync::{Arc, Mutex};
 
 #[derive(Debug)]
@@ -132,7 +133,7 @@ impl<T: Read + Seek> Read for Entry<T> {
                 format!("Failed to lock mutex: {}", e),
             )
         })?;
-        reader.seek(std::io::SeekFrom::Start(
+        reader.seek(SeekFrom::Start(
             self.base_offset + self.header.offset as u64 + self.pos as u64,
         ))?;
         let bytes_read = buf.len().min(self.header.size as usize - self.pos);
@@ -145,6 +146,46 @@ impl<T: Read + Seek> Read for Entry<T> {
     }
 }
 
+impl<T: Read + Seek> Seek for Entry<T> {
+    fn seek(&mut self, pos: SeekFrom) -> std::io::Result<u64> {
+        let new_pos = match pos {
+            SeekFrom::Start(offset) => offset as usize,
+            SeekFrom::End(offset) => {
+                if offset < 0 {
+                    if (-offset) as usize > self.header.size as usize {
+                        return Err(std::io::Error::new(
+                            std::io::ErrorKind::InvalidInput,
+                            "Seek from end exceeds file length",
+                        ));
+                    }
+                    self.header.size as usize - (-offset) as usize
+                } else {
+                    self.header.size as usize + offset as usize
+                }
+            }
+            SeekFrom::Current(offset) => {
+                if offset < 0 {
+                    if (-offset) as usize > self.pos {
+                        return Err(std::io::Error::new(
+                            std::io::ErrorKind::InvalidInput,
+                            "Seek from current exceeds current position",
+                        ));
+                    }
+                    self.pos.saturating_sub((-offset) as usize)
+                } else {
+                    self.pos + offset as usize
+                }
+            }
+        };
+        self.pos = new_pos;
+        Ok(self.pos as u64)
+    }
+
+    fn stream_position(&mut self) -> std::io::Result<u64> {
+        Ok(self.pos as u64)
+    }
+}
+
 struct MemEntry {
     name: String,
     data: MemReader,
@@ -314,11 +355,41 @@ impl<'a, T: Iterator<Item = &'a BgiFileHeader>, R: Read + Seek + 'static> Iterat
                     )));
                 }
             };
+            let reader = MemReader::new(decoded);
+            if reader.data.starts_with(b"BSE 1.") {
+                match BseReader::new(reader, detect_script_type, &entry.header.filename) {
+                    Ok(bse_reader) => {
+                        return Some(Ok(Box::new(bse_reader)));
+                    }
+                    Err(e) => {
+                        return Some(Err(anyhow::anyhow!(
+                            "Failed to create BSE reader for '{}': {}",
+                            entry.header.filename,
+                            e
+                        )));
+                    }
+                };
+            }
             return Some(Ok(Box::new(MemEntry {
                 name: entry.header.filename.clone(),
-                data: MemReader::new(decoded),
+                data: reader,
             })));
         }
+        if buf.starts_with(b"BSE 1.") {
+            let filename = entry.header.filename.clone();
+            match BseReader::new(entry, detect_script_type, &filename) {
+                Ok(bse_reader) => {
+                    return Some(Ok(Box::new(bse_reader)));
+                }
+                Err(e) => {
+                    return Some(Err(anyhow::anyhow!(
+                        "Failed to create BSE reader for '{}': {}",
+                        &filename,
+                        e
+                    )));
+                }
+            };
+        }
         entry.script_type = detect_script_type(&buf, buf.len(), &entry.header.filename).cloned();
         Some(Ok(Box::new(entry)))
     }