OpenRA

Is it possible to add in a feature so you can queue buildings even though they are not available to you. I keep on forgetting what to build and I want to plan out a build order and concentrate more on my army.

that might also fire backwards:
Say you plan to build a specific sequence, but due to events unfolding during the game, you lost a structure, ergo aren't able to build it, but the sequencer was set to build it now but waits ... ... ...;
or without you knowing what might happen, you suddenly need to change the sequence due to the combat situation, so the sequence you command way earlier might be too much to cancel and you end up not building what is needed at that situation, ergo loosing even more buildtime...