I have completed the tutorial top down shooter game recently. This gives you free assets to use for your game. Now I want to build a simple game by myself. Is there any software (preferably free) that can easily make assets? Does the paid version of Construct 2 have an extra extension that lets you make assets?
you can use the animation editor in Construct 2 to draw things but its a bit time consuming compared to other free options and more modern programs, but if you plan on doing original artwork that doesn't require more than 3-5 frames you can achieve that in C2 as well, however if you got 50$ to spare you can use your C2 license and get a 50% discount on the first year and get C3 (if the offer is still available more info about that is somewhere in C3 forum section), C3 has an onion skin for drawing (meaning you can see the before frame which helps on making the 2nd frame and 3rd and so on, and other features that C2 lacks.
if you can't afford photoshop payment every month there is the affinity product that is similar to photoshop and is like C2 payment option where you buy ones you get it forever.
affinity - 50$
if you don't have the funds for it then a lot of designer are using
GIMP
or you can see what this dude showcases on his video
cheap and free photoshop alternatives
there are tons of softwares out there that are completely free, is a matter of picking one where you feel comfortable with the interface and its drawing/method/features. Some allow you to do transparent backgrounds some don't (like paint).