The demons are broken, as 900 demons generate only 879 Sextillion and 1000 mummies generate 1 Septillion. Therefore no reason to get demons at start, it'll just ruin your income.
indeed not bad as a first game. got bit boring after getting weapon level maxed, maybe you should put more levels or give options to choose over some aspects of weapon at certain levels. for instance faster fire rate with lower damage, or opposite, so that you could make your crab's weaponry to suit your own playstyle. i'd give it 4/5
More researches are to be added soon, that achi is a teaser :)