Hey all! OP is in spoilers below, but in case you came looking for a stupid-simple waterlock, I figured I'd update the OP with what people taught me in the course of this thread. Well, not all of it, but the bits that actually stuck. Behold, the corner lock! It is, as advertised, exceptionally simple. It uses ONI's 'one element per tile' rule, as all (?) liquid locks do, to prevent the gasses from transferring from one area to another. This is not a perfectly stable liquid lock,