The original IGI 1 is only ~300 MB. Even heavily compressed, a repack may drop to ~100 MB. For gamers with slow internet or limited data, this small size is attractive.
This is simply the subtitle of the first IGI game. Repeating it in the keyword may be for emphasis or to catch both possible search variations. igi+1+i+am+going+in+portable+fitgirl+repack+exclusive
The "portable installer" might be a wrapper that changes your Chrome/Firefox homepage to a shady search engine or installs adware extensions. The original IGI 1 is only ~300 MB
The search query reveals several gamer needs: but the original does not.
A: No. IGI 1 is strictly single-player. IGI 2 had a multiplayer mode (Team Deathmatch), but the original does not.