The Celeron N2840 is a Bay Trail generation Atom CPU which means it is a very low power consuming CPU, but it also have very low performance compared to their Core i3/i5/i7 CPUs. They are not really meant to play games with because the Intel HD (Bay Trail) graphics core is pretty weak; much weaker than the Intel HD 3000 graphics core released in 2011.
I tested Skyrim on my Lenovo Y470 laptop with the Core i5 CPU (forgot the model number) which has the integrated Intel HD 3000 graphics core as well as a dedicated nVidia GT 550m graphics chip. I disabled the GT 550m to test how well Skyrim can run on the Intel HD 3000. Even with low graphic settings and 720p resolution the game did not run very well on the Intel HD 3000. I had to edit the INI file to further reduce graphic settings (like totally getting rid of grass and shadows) and also download a low texture pack so that Skyrim can run at about 24 FPS with the Core i5 and the Intel HD 3000 which is more powerful than the Celeron N2840.
I have seen a video of a laptop with the N2840 play Minecraft with the Optifine mod to reduce graphics and it seemed to run okay. Will it run LoL with low settings? Maybe...
You would have to drop you Screen resolution down and lower the game settings to get decent FPS in Skyrim. Low settings and 800X600 at best. That is why I suggested a AMD APU based system for around the same price and they will game much better with much higher settings.