Not easy to get laptop with "ultrabook" label with your budget

But your usage requirement definitely is not demanding. Intel HD 4000 can handle Dota2

Please make sure you have good external cooling solution when you game on (light and thin) laptopĀ
Asus
K46CB-WX060H, i5-3337U + Nvidia GT740M@RM2199[2kg], 2GB, 750GB, W8, 4-cell, OD
K46CM-WX059V, i3-3217U + Nvidia GT635M@RM1899[2kg], 2GB, 500GB, 4-cell battery, W7HP, OD
Dell
Vostro 5460, i3-3120M + Nvidia GT630M@RM1949[1.54kg], 4GB, 500GB(5400rpm), W8SL, 3 cell
Vostro 5460, i5-3230M +Nvidia GT630M@RM1899[1.54kg], 4GB, 500GB(5400rpm), Ubuntu 12.04, 3 cell; W8SL@RM2099
HP
Envy4-1238TX, i5-3337U + AMD HD8750M@RM2099[Beats][1.75kg], 2GB, 500GB(5400rpm), W8
Prices are RSP, negotiable.
Err. Then is there any other options? I mean not really need to be thin & light, since my budget is just 1.7k. thanks