diff --git a/WeKan-Multiverse-Roadmap.md b/WeKan-Multiverse-Roadmap.md
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--- a/WeKan-Multiverse-Roadmap.md
+++ b/WeKan-Multiverse-Roadmap.md
@@ -1,3 +1,16 @@
+## What is not Cross-Platform
+
+- Requires CPU to support AVX
+  - Bun Javascript Engine https://bun.sh
+  - MongoDB 5.x and newer https://github.com/turnkeylinux/tracker/issues/1724#issuecomment-2351544191
+- Does not work at s390x
+  - V programming language https://github.com/vlang/v/issues/18737
+  - Bun Javascript Engine https://github.com/oven-sh/bun/issues/2632
+  - Deno Javascript Engine https://github.com/denoland/deno/issues/20212#issuecomment-1756663943
+  - Lazarus IDE https://www.lazarus-ide.org
+    - FreePascal programming language https://www.freepascal.org
+  - TigerBeetle database https://github.com/tigerbeetle/tigerbeetle/issues/2241
+
 ## Prototype Strategy
 
 - Try building many prototypes, see what works