diff --git a/todo.md b/todo.md
index 2006512..b36b3bb 100644
--- a/todo.md
+++ b/todo.md
@@ -1,8 +1,8 @@
 ## 1. refine existing engine (knowing what I know now)
 
-- [ ] rewrite event queue as a linked list
-- [ ] rewrite animator stacks as linked lists
-- [ ] rewrite ship/bullet collections as linked lists
+- [x] rewrite event queue as a linked list
+- [x] rewrite animator stacks as linked lists
+- [x] rewrite ship/bullet collections as linked lists
 - [ ] update/draw mode switching system (high-efficiency version)
 - [ ] render ship shields (even for large ships)
 - [ ] duplicate file -- about to split away from Tyrian features