Open-ended fitness landscape or architectural innovation is a key characteristic of technological evolution. Though many have argued that this feature is important, many models were created in a closed fitness landscape. In this article, we used a computer simulation to investigate (1) whether the speed of innovation is increased by increasing group size and (2) if the nature of innovation would differ when innovation was separated by invention (new innovation that serves a purpose that never was used before) and improvement (already made innovation but is more efficient). The results indicated that indeed group size increases the speed of innovations but is limited than expected. Also, when innovation was separated with invention and improvement, the nature of the two differed. In invention, the trajectory resembled the technology s-curve with a continuous pattern of rapid increase followed by a plateau. In improvement, the trajectory followed a function with square root times the group size, meaning that the productivity of one agent decreases as group size increases.