It's why I started to look thro HMC posts... I know absolutely nothing about MOTO. I want to try to understand how it works... Looks like I will need to look into source too... 'Allowed time' doesn't serve as difficulty well... And I don't remember if he told anything about map difficulty (although subjectively for me it's seems that it's definitely harder when there are more miners around). (EDIT: he told about Perlin noise 'difficulty' - post from June 11 2014, but I still do not sure if it was implemented in some way. I need to continue to read the thread, I'm on 42nd page just now). In short words: what the miracle is that 'anti-warp' feature?.. Maybe it can serve not only MOTO, but other cryptos as well...
Anti warp is to prevent time warp attacks (HMC started to call it this way). Difficulty is adjusted using maximum allowed time, however it cannot drop below the median time of last N blocks (this is to prevent making mining impossible). Say if target time is 30 seconds and you generate only 30 seconds replays then time will never drop below 30 seconds, if you can genereate 30 second replay each second you can instamine many blocks and difficuly will not increase to counter that. Anti warp adds classical PoW to map generation to prevent this.