Our fourth edition of Weird + Small Apps practically defines the very reason we created this weekly column: between the bizarre Japanese-developed Tissue, the micro-games Derzle and Mental Blocks, and the small apps Mental Maths and Puppet, these are titles that are tiny but worth sharing. If you’re looking for the most unusual pick of the week, and perhaps the last month, go straight to Tissue. We’ll gladly take suggestions if you’ve…