If this is the spiritual successor to Jagged Alliance 2, things don't bode well for JA3.
It's a shame then that there is no actual game to compliment the combat engine. You watch a cut scene that informs you you're in some fictitious South American country as a mercenary, you had been taken prisoner and then released and compelled to work for...someone. From this you're launched into a multiple choice quiz which allows you to fine tune your character. You also select which of the three in game factions you wish to ally yourself with.
From there, you're launched into the game world and a dull world it is. You are presented with an overhead map and you select travel destinations on that map. You then set a slider with allows to to control the route and speed of movement. You can set it for maximum speed which will follow the road, or maximum cover and awareness which will slow you down but make ambushes much less likely.
Destinations on the map are gradually revealed as you pass by or are informed of them by NPC encounters. These encounters are typically dull, lifeless affairs filled with uninspiring, generic dialogue. These cardboard cut out NPCs also give you jobs to do to earn cash which you use to hire fellow mercenaries and buy new gear, vehicles, etc. The jobs are pretty dull, time limited affairs along the lines of "deliver good A to city B within X number of days and you'll get Y amount of dollars." or "Kill X gangsters before Y day and you'll get a reward."
It really feels unfinished and bare bones. I'm a little surpirsed by this as previews for the game all made a point of letting people know that the JA2 script writer was involved in creating E5.
Graphics are pretty spartan. Terrain looks especially poor. Sounds aren't much better.