diff --git a/_custom_jump.asm b/_custom_jump.asm
new file mode 100644
index 0000000..899c1e2
--- /dev/null
+++ b/_custom_jump.asm
@@ -0,0 +1,67 @@
+_custom_jump:
+if CUSTOM_JUMP_BANK == PLAYER_UPDATE_BANK
+    jsr rts_if_cutscene
+    JSR zero_hspfra
+else
+    ; return if in cutscene
+    lda cutscene_timer
+    beq __continue
+    lda cutscene_input
+    beq __continue
+    rts
+__continue
+
+    ; zero out fractional hspeed
+    lda #$00
+    sta hspfra
+endif
+    LDA joypad_down
+    AND #$03 ; 1=right, 2=left
+    BEQ hcancel
+    LSR A
+    BCC air_control_left
+    
+air_control_right:
+    ; if left and right, hcancel
+    LSR A
+    BCS hcancel
+    
+    ; standard right
+    LDY #$00
+    LDX #$01
+    STX hspint
+    BPL __jumping_contd ; guaranteed
+air_control_left:
+    LDY #$01
+    LDX #$FF
+    STX hspint
+__jumping_contd
+
+    ; decide whether or not to set facing
+    LDA simon_state
+    CMP #8 ; jumping
+    BNE check_vcancel
+    LDA imgsin
+    CMP #$10
+    
+set_facing:
+    BEQ check_vcancel
+    STY facing
+    BNE check_vcancel ; guaranteed
+    
+hcancel:
+    STA hspint
+    
+check_vcancel:
+    LDA joypad_down
+    AND #$80 ; holding jump button?
+    BNE __vcancel_rts
+    LDA vspint ; already moving downward?
+    BPL __vcancel_rts
+    
+    LDA #VSP_CONTROL_ZERO_VSPEED
+    STA vsp_control
+    LDA #$00
+    STA vspint
+__vcancel_rts:
+    RTS
\ No newline at end of file
diff --git a/_custom_knockback.asm b/_custom_knockback.asm
new file mode 100644
index 0000000..f4a87b5
--- /dev/null
+++ b/_custom_knockback.asm
@@ -0,0 +1,30 @@
+_custom_knockback:
+    ; if 0 hp, do normal knockback
+    LDA hitpoints
+    BEQ __return_to_knockback
+    
+    LDA vspint
+    BMI custom_knockback_moving_upward
+    
+    LDA #8 ; jumping
+    STA simon_state
+    LDA $49
+    BEQ custom_knockback_moving_upward
+    LDA $48
+    CMP #$02
+    BNE custom_knockback_moving_upward
+    LDA #$38
+    STA vsp_control
+    LDA #$16
+    STA imgsin
+    JMP __return_to_knockback
+    
+custom_knockback_moving_upward:
+    LDA #VSP_CONTROL_ZERO_VSPEED
+    STA vsp_control
+    LDA $A689,Y
+__return_to_knockback:
+    ; resolve detour
+    LDA #8
+    LDY hspint
+    RTS
\ No newline at end of file
diff --git a/build.sh b/build.sh
index 08508ba..6a6c527 100755
--- a/build.sh
+++ b/build.sh
@@ -1,21 +1,29 @@
-BASE=base.nes
-SRC=patch.asm
+BASE=base
+SRC=patch
 OUT=out
 
-echo "INCNES \"$BASE\"" > inc-base.asm
-which asm6f > /dev/null
-if [ $? != 0 ]
-then
-    echo "asm6f is not on the PATH."
-    continue
-fi
+builds=("us" "jp")
 
-asm6f -c -n -i "-dUSEBASE" "$SRC" "$OUT.nes"
+for build in "${builds[@]}"; do
+    if [ ! -f $BASE-$build.nes ]; then
+        echo "no base: $BASE-$build.nes"
+        continue
+    fi
+    echo "INCNES \"$BASE-$build.nes\"" > inc-base.asm
+    which asm6f > /dev/null
+    if [ $? != 0 ]
+    then
+        echo "asm6f is not on the PATH."
+        continue
+    fi
 
-if [ $? != 0 ]
-then
-    echo "error building."
-    exit
-fi
+    asm6f -c -n -i "-dUSEBASE" "-dBUILD_${build^^}" "$SRC-$build.asm" "$OUT-$build.nes"
 
-ipsnect "$OUT.ips" > "$OUT.map"
\ No newline at end of file
+    if [ $? != 0 ]
+    then
+        echo "error building."
+        exit
+    fi
+
+    ipsnect "$OUT-$build.ips" > "$OUT-$build.map"
+done
\ No newline at end of file
diff --git a/offsets-jp.asm b/offsets-jp.asm
new file mode 100644
index 0000000..2ac4020
--- /dev/null
+++ b/offsets-jp.asm
@@ -0,0 +1,16 @@
+detour_to_custom_knockback=$8338
+standard_crouch=$9920
+trevor_jump_table=$9376
+attack=$942F
+jump_attack_step=$94C9
+set_fall_state=$974F
+fall_adjust=$9756
+standard_jump=$9777
+standard_stair_idle=$99A4
+standard_stair_walk=$9AAB
+sypha_jumptable=$9C19
+alucard_jumptable=$A59B
+empty_bank_e=$BF39
+setAndSaveLowerBank=$E2D0
+PLAYER_UPDATE_BANK=$E
+CUSTOM_JUMP_BANK=$E
\ No newline at end of file
diff --git a/offsets-us.asm b/offsets-us.asm
new file mode 100644
index 0000000..95a504a
--- /dev/null
+++ b/offsets-us.asm
@@ -0,0 +1,17 @@
+detour_to_custom_knockback=$834D
+standard_crouch=$9919
+trevor_jump_table=$9381
+attack=$943A
+jump_attack_step=$94D4
+set_fall_state=$9748
+fall_adjust=$974F
+standard_jump=$9770
+standard_stair_idle=$998E
+standard_stair_walk=$9A93
+sypha_jumptable=$9C02
+alucard_jumptable=$A5B4
+empty_bank_e=$BFAB
+empty_bank_0=$BED0 ; we actually can go a bit earlier
+setAndSaveLowerBank=$E2E6
+PLAYER_UPDATE_BANK=$E
+CUSTOM_JUMP_BANK=$0
\ No newline at end of file
diff --git a/out-jp.ips b/out-jp.ips
new file mode 100644
index 0000000..96212ec
Binary files /dev/null and b/out-jp.ips differ
diff --git a/out-us.ips b/out-us.ips
new file mode 100644
index 0000000..d6afd87
Binary files /dev/null and b/out-us.ips differ
diff --git a/patch.asm b/patch-jp.asm
similarity index 90%
rename from patch.asm
rename to patch-jp.asm
index 4fcac3a..7e8485f 100644
--- a/patch.asm
+++ b/patch-jp.asm
@@ -2,7 +2,8 @@
 
 include "pre.asm"
 
-include "ram.asm"
+include "ram-jp.asm"
+include "offsets-jp.asm"
 
 VSP_CONTROL_ZERO_VSPEED=$1C
 
@@ -16,7 +17,7 @@ getting_hit:
 FROM $8307
 knockback_step:
 
-FROM $8338
+FROM detour_to_custom_knockback
     NOP
     NOP
     JSR custom_knockback
@@ -25,20 +26,16 @@ FROM $8AC6
 standard_state_0:
 
 ; in Trevor state jump table ($9376)
-FROM $9376
-trevor_jump_table:
-
-FROM $937E
+FROM trevor_jump_table
+SKIP $8
     ; state 8 (jumping)
     ; jump replacement
     DW custom_jump_then_standard_jump
 
-FROM $942F
-attack:
+FROM attack
     jsr jumping_attack
 
-FROM $94C9
-jump_attack_step:
+FROM jump_attack_step
     jsr jumping_attack
 
 FROM $952D
@@ -50,11 +47,11 @@ standard_begin_jump:
 FROM $9667
 standard_walk:
 
-FROM $974F
+FROM set_fall_state
     ; go to jump state (instead of falling state)
     lda #$08
 
-FROM $9756
+FROM fall_adjust
     ; x=0 before this
     lda #VSP_CONTROL_ZERO_VSPEED
     STA vsp_control,X
@@ -75,50 +72,42 @@ rts_if_cutscene:
     pla
     pla
     rts
-LIMIT $9777
-
-FROM $9777
-standard_jump:
+LIMIT standard_jump
 
-FROM $9920
-standard_crouch:
+FROM standard_crouch
     jsr crouch_direction
 
-FROM $99A4
-standard_stair_idle:
+FROM standard_stair_idle
     ; replaces:
         ; LDA joypad_down
         ; AND #$40 ; down ?
     JSR stair_jumping
     NOP
     
-FROM $9AAB
-standard_stair_walk:
+FROM standard_stair_walk
     ; replaces:
         ; JSR $9A43
     JSR stair_jumping
 
-FROM $9C19
-sypha_jumptable:
+FROM sypha_jumptable
 
-FROM $9C21
+SKIP $8
+    ; jump
     DW custom_jump_then_standard_jump
 
-FROM $A59B
-alucard_jumptable:
-
-FROM $A5A3
+FROM alucard_jumptable
+    SKIP $8
     DW custom_jump_then_standard_jump
 
 ; custom code
-FROM $BF39
+FROM empty_bank_e
     LDA #$01
     STA hspint,X
 custom_jump_then_standard_jump:
     ; push return address (-1)
-    LDA #$97
+    LDA #>standard_jump
     PHA
-    LDA #$76
+    LDA #<standard_jump-1
     PHA
 custom_jump_jsr:
     jsr rts_if_cutscene
diff --git a/patch-us.asm b/patch-us.asm
new file mode 100644
index 0000000..5799b4a
--- /dev/null
+++ b/patch-us.asm
@@ -0,0 +1,207 @@
+; must be built using build.sh
+
+include "pre.asm"
+
+include "ram-us.asm"
+include "offsets-us.asm"
+
+VSP_CONTROL_ZERO_VSPEED=$1C
+
+; --------------------------------------------------------------------
+BANK $E
+BASE $8000
+
+FROM $81FE
+getting_hit:
+
+FROM $8307
+knockback_step:
+
+FROM detour_to_custom_knockback
+    ; replacement:
+        ; lda #$08
+        ; ldy $04F2
+    NOP
+    NOP
+    JSR custom_knockback
+
+; in Trevor state jump table ($9376)
+FROM trevor_jump_table
+SKIP $8
+    ; state 8 (jumping)
+    ; jump replacement
+    DW custom_jump_then_standard_jump
+
+FROM attack
+    jsr jumping_attack
+
+FROM jump_attack_step
+    jsr jumping_attack
+
+FROM set_fall_state
+    ; go to jump state (instead of falling state)
+    lda #$08
+
+FROM fall_adjust
+    ; x=0 before this
+    lda #VSP_CONTROL_ZERO_VSPEED
+    STA vsp_control,X
+    STX simon_fall_objphase
+    lda #$16
+    sta imgsin
+zero_hspfra:
+    lda #$00
+    sta hspfra
+__standard_rts:
+    rts
+rts_if_cutscene:
+    lda cutscene_timer
+    beq __standard_rts
+    lda cutscene_input
+    beq __standard_rts
+    ; double-rts -- rts caller
+    pla
+    pla
+    rts
+LIMIT standard_jump
+
+FROM standard_crouch
+    jsr crouch_direction
+
+FROM standard_stair_idle
+    ; replaces:
+        ; LDA joypad_down
+        ; AND #$40 ; down ?
+    JSR stair_jumping
+    NOP
+    
+FROM standard_stair_walk
+    ; replaces:
+        ; JSR $9A43
+    JSR stair_jumping
+
+FROM sypha_jumptable
+
+SKIP $8
+    ; jump
+    DW custom_jump_then_standard_jump
+
+FROM alucard_jumptable
+    SKIP $8
+    DW custom_jump_then_standard_jump
+
+; custom code
+FROM empty_bank_e
+
+stair_jumping:
+    ; pressed jump button?
+    LDA joypad_pressed
+    AND #$80 ; (pressed jump)
+    
+    BEQ __recover_step
+    
+    ; perform jump
+    LDA #$06 ; begin jump
+    STA simon_state
+    
+    ; double-return
+    ; (quit out of stair logic as well)
+    PLA
+    PLA
+    RTS
+    
+__recover_step:
+    ; here we perform the detour logic to resume a standard tick
+    ; however, we must do different logic depending on state/call site
+
+    LDA simon_state
+    CMP #$14 ; stair walk
+    BEQ __recover_stair_walk
+__recover_stair_idle:
+    LDA joypad_down
+    AND #$40
+    RTS
+__recover_stair_walk:
+    JMP $9A43
+
+crouch_direction:
+    LDA joypad_down
+    LSR A
+    BCC +
+    LDX #$00
+    STX facing
++
+    LSR A
+    BCC +
+    LDX #$01
+    STX facing
++
+    ; resolve detour: trampoline
+    JMP $840C
+  
+custom_knockback:
+    lda #((CUSTOM_JUMP_BANK << 1) | $80)
+    jsr setAndSaveLowerBank
+custom_knockback_bankswap_loc:
+    rts
+    
+custom_jump_then_standard_jump:
+    ; push return address (-1)
+    LDA #>standard_jump
+    PHA
+    LDA #<standard_jump-1
+    PHA
+custom_jump_jsr:
+    ; not sure why we | #$80 but it seems everything else does
+    lda #((CUSTOM_JUMP_BANK << 1) | $80)
+    jsr setAndSaveLowerBank
+custom_jump_bankswap_loc:
+    rts
+
+jumping_attack:
+    JSR custom_jump_jsr
+    JMP $97A3 ; .. not necessarily air-attacking?
+    
+LIMIT $C000
+
+; --------------------------------------------------------------------
+BANK $0
+BASE $8000
+
+FROM empty_bank_0
+    include "_custom_jump.asm"
+    include "_custom_knockback.asm"
+end_bank_0_core:
+    
+FROM custom_knockback_bankswap_loc-5
+ATLEAST end_bank_0_core
+custom_knockback_bankswap_loc_pre:
+    lda #((PLAYER_UPDATE_BANK << 1) | $80)
+    jsr setAndSaveLowerBank
+    
+    ; (bankswap)
+    EXACT custom_knockback_bankswap_loc
+    
+    jsr _custom_knockback
+    jmp custom_knockback_bankswap_loc_pre
+end_custom_knockback_bankswap_tramp
+    
+FROM custom_jump_bankswap_loc-5
+ATLEAST end_custom_knockback_bankswap_tramp
+custom_jump_bankswap_loc_pre:
+    lda #((PLAYER_UPDATE_BANK << 1) | $80)
+    jsr setAndSaveLowerBank
+    
+    ; (bankswap)
+    EXACT custom_jump_bankswap_loc
+    
+    jsr _custom_jump
+    jmp custom_jump_bankswap_loc_pre
+end_custom_jump_bankswap_tramp:
+    
+; --------------------------------------------------------------------
+BANK $F
+BASE $C000
+
+; jump by table
+FROM $E814
\ No newline at end of file
diff --git a/pre.asm b/pre.asm
index 60b9078..76d9d5e 100644
--- a/pre.asm
+++ b/pre.asm
@@ -36,6 +36,12 @@ MACRO BANK8 bank
     SEEK (bank * $2000) + $10
 ENDM
 
+MACRO ATLEAST pos
+    if ($ < pos)
+        ERROR exceeded room! $ > pos
+    endif
+ENDM
+
 MACRO LIMIT pos
     if ($ > pos)
         ERROR exceeded room! $ > pos
diff --git a/ram.asm b/ram-jp.asm
similarity index 96%
rename from ram.asm
rename to ram-jp.asm
index 829e75e..0865235 100644
--- a/ram.asm
+++ b/ram-jp.asm
@@ -91,7 +91,6 @@ BASE $0028:
 BASE $002A:
     joypad_down:
 
-
 BASE $0506:
     dagger_hspint:
 
@@ -134,11 +133,8 @@ BASE $000B:
 BASE $0008:
     tmp_y:
 
-BASE $003A
-    partner_us:
-
 BASE $0048
-    partner_jp:
+    partner:
     
 BASE $780
     cutscene_timer:
diff --git a/ram-us.asm b/ram-us.asm
new file mode 100644
index 0000000..c5697b7
--- /dev/null
+++ b/ram-us.asm
@@ -0,0 +1,60 @@
+BASE $0021:
+    _bank:
+
+BASE $0026:
+    joypad_pressed:
+
+BASE $0028:
+    joypad_down:
+
+BASE $003A
+    partner:
+
+BASE $0565:
+    simon_state:
+
+BASE $0520:
+    vspint:
+    
+BASE $05D8:
+    vsp_control:
+
+BASE $003A:
+    hitpoints:
+    
+BASE $0400:
+    imgsin:    
+
+BASE $04A8:
+    facing:
+
+BASE $04F2:
+    hspint:
+    
+BASE $041C:
+    yint:
+    
+BASE $0438:
+    xint:
+    
+BASE $0509:
+    hspfra:
+
+BASE $0537:
+    vspfra:
+
+BASE $04C4:
+    xfra:
+
+BASE $04DB:
+    yfra:
+    
+; TODO: double check these!
+BASE $780
+    cutscene_timer:
+    
+BASE $783
+    cutscene_input:
+    
+BASE $05C1:
+    simon_fall_objphase:
\ No newline at end of file